Forcefield Back Protector Pro Sub 4
  • Forcefield Back Protector Pro Sub 4
  • Forcefield Back Protector Pro Sub 4
  • Forcefield Back Protector Pro Sub 4
  • Forcefield Back Protector Pro Sub 4
  • Forcefield Back Protector Pro Sub 4
  • Forcefield Back Protector Pro Sub 4

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Forcefield Back Protector Pro Sub 4

The Forcefield Back Protector Pro Sub 4 is the worlds first Motorcycle back protector to transmit less than 4kn when subjected to the standard CE test.

The Pro Sub 4 has been specifically designed to test at under 4kn when subjected to the standard CE test EN1621-2. Independent testing by SATRA shows a mean test result of 3.38kn transmitted energy, making it the first motorcycle back protector in the world to attain this level of performance. Constructed with a removable and washable outer cover to give the rider the ability to keep the back protector clean and hygienic, it also makes the protector more flexible as it is not bonded at the edges, this in turn makes it more comfortable to wear, a prime consideration in the design process of any Forcefield product. As with all Forcefield Body Armor, the Pro Sub 4 has RPT (Repeat Performance Technology) ensuring continued and consistent protection even after multiple impacts. 


  • Removable and washable outer cover
  • CE Level 2 Rated Protection
  • RPT (Repeat Performance Technology)
  • Comfortable and non restrictive
  • Flexible
  • Breathable
  • Molds to body shape
  • Adjustable waist and shoulder straps
  • Multi Sport use
4.7 / 5
Bang For The Buck
4.4 / 5
Protection & Durability
4.8 / 5
4.5 / 5
4.5 / 5
4.3 / 5
Air Flow
4.2 / 5

Forcfield Men's Pro Sub 4 Back Protector Sizing

Size Torso Length (in)
SM >16
MD 16.5-18.25
LG 18.5-19.75
XL 20+


Sizing information is provided by the manufacturer and does not guarantee a perfect fit.

How To Measure

TL Torso Length While standing upright, measure the distance between your waist (typically at navel or top of the hip bone level) and the top of your shoulder, to the left or right of your spine.
Product Style RevZilla Item # Manufacturer Product # Availability
SM 617815 FPS-4-2-S In Stock: Ships within 24 hours
MD 617816 FPS-4-2-M Available: Requires 2-3 business days lead time prior to shipment
LG 617817 FPS-4-2-L In Stock: Ships within 24 hours
XL 617818 FPS-4-2-XL Out of Stock


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See our full Shipping Policy for further details.


If your order arrives and it is not right, we will we'll fix it, NO NONSENSE, we promise.

Doesn't fit or just not happy with it? You can return any new, unused and unaltered item within 30 business days of delivery receipt of your item. We will issue a full refund to your original payment method.

See our full Return Policy for all of the pertinent details.

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Have a functionality, fit, or otherwise product-specific question about the Forcefield Back Protector Pro Sub 4? Ask it here! If you have a customer service or shipping question, please direct it to our Customer Service department.

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Browse 7 questions Browse 7 questions and 75 answers
Why did you choose this?
RevZilla Store
Best back protector out there.
Carol S on Jul 17, 2017
Top product after lots of my research in the internet
Pham T on May 27, 2017
Best back protector out there.
Carol S on Jul 17, 2017
khachik a on Jul 15, 2017
Top product after lots of my research in the internet
Pham T on May 27, 2017
safety and design
Aaron S on May 5, 2017
Recommendation from experienced racers.
Robert H on Mar 10, 2017
It's the best back protector for the money.
Alberto P on Aug 11, 2016
I wanted the best for my own comfort and safety.
John D on Jul 8, 2016
I wear this back armor inside my Dainese one-piece leathers on the track.
This is essential gear for track days.
JD D on May 9, 2016
many reviews spoke highly of the product.
fernando c on Feb 8, 2016
Best back protection
Henry L on Dec 28, 2015
Supposed to be best in class.
Wore it for 3 years now. Comfortable, not too bulky. Did me well on a couple lowsides.
multispoke on Nov 29, 2015
It cover a lot more going all the way down to the lumbar area and its sub 4, also it very low profile so I can wear it under the cloth.
Jaime I on Nov 27, 2015
To protect myself in the event of a fall
G S on Nov 9, 2015
reviews seemed strong. Looking for a top of the line back protector
Rob M on Aug 24, 2015
Best in class back protection.. nothing better
Jon W on Jun 28, 2015
Called & spoke to CS rep. He suggested this brand as a stand alone back protector. Good reviews on this item as well.
Bob C on Jun 22, 2015
Best back protector
Leith D on Feb 22, 2015
Wanted to try a new back protector plus it was on sale.
Alexander N W on Feb 14, 2015
After researching for a long time I decided for this back protector because it really seen the best one around. Now is just wait to comprove or have a disappointment. But I'm really confident that I make the right choice
rafafreedom on Feb 6, 2015
"The best protection you can get. And, it breathes well and conforms to your body."
Tyler E on Dec 16, 2014
It seemed silly to buy an intermediate or less expensive back protector when spine safety is the issue. I reviewed the specs on a range of protectors and this clearly is the best on the market. As far as I can tell a no-brainer.
A B on Dec 6, 2014
I am a dad now and was looking for the best protection I could get.
Tom M on Nov 24, 2014
After careful review and extensive research the "Forcefield Back Protector Pro Sub 4" simply offered the highest level of protection through unparalleled shock absorption and energy disbursement. Although a bit more cumbersome than the insert version, it's a trade off I can live with!
Richard M on Nov 24, 2014
Recommendation of trusted and very experienced friend, along with very high ratings in numerous reviews and surveys.
Harry S on Sep 22, 2014
Safety and quality. Haven't been disappointed. Great product.
manuel s on Aug 8, 2014
It costs alot so it should do a better job than a cheap back protector....... right?
Wilfred F on May 28, 2014
After a lot of research, found this to offer the best protection that is available in the market for the back and spine
Sunbir W on Apr 15, 2014
Best protection
Justin R on Apr 12, 2014
Safest back protector on the market
"" " on Feb 16, 2014
It´s suposed to be the best back protector.
JUAN R on Feb 14, 2014
It's the best body armor made! Since you carry almost all of the Forcefield line of products, may I recommend that you take a look at carrying just a few of their other items for snow sports too? I am talking about the Board Shorts (tinyurl . com/kknpfgt), Knee Protectors (tinyurl . com/lrqhxz7), and Boom Shorts (tinyurl . com/omdsz83). Trust me. There's a market for it. I had to order shorts and knee guards from England, but would rather have paid you! Thanks!
Jeff R on Dec 31, 2013
Had a wreck & broke my back in 4 places. I was wearing a jacket with a CE approved spine protector. Had I been wearing this I would not have spent six weeks in hospital & not have had to learn to walk all over again. This is CHEAP INSURANCE! It is also comfortable & you forget you are wearing it. Don't be so COOL it kills you.
Mark on Dec 17, 2013
Wade S on Oct 26, 2013
How could I not choose Forcefield for my spine protection. All it takes is for one fall and without the proper protection and you just can't take it back, This product screams safety fits well right out of the box, I highly support all forcefield for making the best safety products on the market.
Johnny Busa on Oct 2, 2013
I love Forcefield and did a lot of research before purchasing this. It is quite thick but very light and comfortable. Great protection but too thick under the tight fitting kangaroo suit, switched to the ladies Pro Sub 4 (which was not available when I purchased this).
Athena M on Sep 26, 2013
khachik a on Jul 15, 2017
safety and design
Aaron S on May 5, 2017
How thick is this back protector? I have read in numerous reviews that you need to account for the extra room beneath your riding gear. How much extra room are we talking here? I currently have a Dainese Thorax Wave Pro (too big for me, and smaller size is unavailable). Would it take up a similar amount of room?
A shopper on May 20, 2014
BEST ANSWER: It is quite thick, though in comparison to the dainese it is more flexible and more comfortable. It is probably 3/4"-1" thick.

This probably won't be an apples to apples comparison, as the Thorax Wave pro is a whole armor jacket with chest protector - or did you mean just their bac protector?
Hey. I'm just under of 5 11", 32" waist, 178lbs. I took the torso measurment as advised by forcefield and keep coming up 21-22". I'm usually a medium in everything and the 22" puts me into an XL. Would you think the L would do it? thanks. tim
Tim F on Aug 18, 2013
BEST ANSWER: I'm not sure why this thing says my name is Mary, but whatever. I'm personally 5'9", 160 lbs, and about a 31 inch waist and I ordered a medium and it fits but it may be a hair too small. But it's so close that a large would have been too long. Best thing I can tell you to do is order a large because that should work for you as put it on with the gear you plan to wear with it, helmet too. The back protector should cover your tailbone with the tip, all the way up to your neck pretty much. Should be about an inch of space between the top of the back protector and your helmet. Make sure it's not bunched up or caught on your gear too as that would give you an inaccurate idea of how it fits. If its too short, go up to an XL if its way too long (doubtful) go down a size. Most likely though, I'd guess a large would do you. But it's worth it to send it back if its not right because the more uncomfortable it is, the more likely you are to not wear it or become distracted while riding. Hope that helps!
Hi guys,

Looking at the Pro Sub 4, trying to determin the right size.
I am 5'11" or 6 foot depending on the day and the ruler, I am thin though which affects the waste straps. 34" waist. According to the size chart I would probably be at the edge of medium and the beginning of large. My instinct is to go for the longer large but I am concerned the straps will be too stout.
What do ya' think?

A shopper on Jul 15, 2011
BEST ANSWER: I am 6'2" and 210 pounds. I use the large ProSub4 and it is perfect. I would think that the medium might be better for your height and thin build as you described. My only reservation would be if you have a very long which case you might need the extra length of the large. The straps on the large also might give you too much material and be a bit sloppy under your suit. They gave a lot of material for a huge spectrum of torsos, which you don't need to worry about. Go Medium...and Revzilla is amazing at return/exchanges so you can't go wrong.
Is there a similar level chest protection?
A shopper on May 15, 2014
BEST ANSWER: In terms of thickness and impact absorption, no; however, the Forcefield chest protector is more than enough. It is still thicker than most and made up of the same layering of composites and it lets the air pass through to your chest. I do not feel ready to ride unless I am wearing the Pro Sub-4 and the chest protector.
Make sure everything fits under your leathers. I got measured up for a set of custom leathers with my chest and back protector on and I am so glad that I did. While the back protector or chest protector might fit under your existing leathers, together, they are unlikely to fit unless you leather are too big. otherwise.
How well will this fit under an Atem suit?
Ed V on Sep 18, 2014
BEST ANSWER: This is an excellent product; however, it does add quite a bit of volume to the body. Whether it fits depends upon how tight/loose your jacket and pants are. I wear my back protector (and a Forcefield chest protector) under a two-piece suit that was made to measure; the additional volume of this equipment is such that I took my measurements with the gear on, adding inches to my circumference. I have an off-the-rack one-piece race suit that is a snug fit and thus this set-up (even without the chest protector) does not fit in that suit.
I currently use an older Technic/Knox full back protector, but it is 10 years old and of the one shot variety. I am very impressed with the specs on the L4 unit and the fact that taking a hit will not deplete from its ability to take another impact at the same point. However, it seems to be made out of a rubbery material and I am wondering how long it's good for until it starts decomposing? Is there a warranty?
Benjamin K on Feb 25, 2014
BEST ANSWER: Hi! I do not know if any warranty? I have one and like it, not sure now how long I had it - I guess about 2 years or so. It is very good and seem to me will last many years! I live where it gets to around 45 C or 120 F in the summer! I have no problems with the sub4 and ware it when every I ride my bikes. both on and off the road.

Yes, expensive, but I believe will be happy with it over the short and long run - I am!
Oh! If tight jacket - will need to get a bigger size with the sub4.
Mr H