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Alpinestars Nucleon Back Protector Insert
  • Alpinestars Nucleon Back Protector Insert
  • Alpinestars Nucleon Back Protector Insert

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Alpinestars Nucleon KR-2i Back Protector Insert

The Alpinestars Nucleon KR-2i Back Protector Insert fits all Alpinestars jackets and race suits and delivers CE Level 2 impact protection.


  • CE Certified Level 2 (EN1621-2:2014)
  • Lightweight, flexible PU injected impact foam
  • Contoured for anatomical and adaptive fit
  • Perforated for breath-ability and comfort
  • Channel ventilation system for optimized airflow

Note: Size MD is recommended for Men's jackets size 50 and smaller and XS-MD. Size LG is recommended for Men's jackets size 52 and larger and LG-4XL. See specific Women's jackets for sizing recommendations.

Sizing Info:

Waist to Shoulder (in) Height (in)  Protector Size
15 - 17 56.75 - 64.25 SM
17 - 19 64.25 - 71.75 MD
19 - 20 71.75 - 76.5 LG

Product Style RevZilla Item # Manufacturer Product # Availability
SM 973533 6501615-10-S In Stock: Ships within 24 hours
MD 973534 6501615-10-M In Stock: Ships within 24 hours
LG 973535 6501615-10-L In Stock: Ships within 24 hours


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We show real-time availability on this product page when you select the size/color item you want.  Most items will ship the same business day an order is placed,however if an item requires additional processing time a message will be shown indicating such.

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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Alpinestars Nucleon Back Protector Insert 4.8 5 63 63
A no brainer! With only comfort foam for back protection in my Astars T GP Pro jacket I began to get a little nervous! CE2 protection, good air flow even with my backpack and reasonably priced. May 24, 2016
Great Protection I used this to replace the stock "foam" in my Alpinestar jacket. The original foam is similar to egg carton foam and just doesn't cut it for protection. This product though is leaps and bounds better. It still contours great and provides plenty of air flow still so I am very pleased with the end result. Would highly recommend this to everyone for the added protection. May 10, 2016
Excellent Upgrade Purchased this along with the chest protectors (Which I also recommend) as an upgrade after a year with my Alpinestars T-GP Plus R Air jacket. The first thing I noticed was the added weight. The jacket feels like it weighs as much as my Alpinestars GP Plus Leather Jacket, but with way better ventilation. That said, the ventilation is slightly reduced as well but is still very, very good. Are these cons enough to make me regret upgrading? Absolutely not. I've been a rider for over 15 years and have never felt this well protected after this upgrade. Having the peace of mind I will be better prepared for whatever might come across on the street more than offsets the downsides. I highly recommend this upgrades! May 10, 2016
Solid back protector I bought this for my girlfriends jacket. The jacket was already fairly snug without the protector. I was worried that with the protector, the jacket would be too tight, but it hasnt seemed to make much of a difference with the back protector in. Solid product from A*, and Revzilla was super fast in shipping as always. May 6, 2016
Very good protector! Very good protector fits ok. I think is good for your back. April 26, 2016
Just what I was looking for I purchased this as an upgrade for the flimsy piece of foam that came in my Sedici jacket. It fitted perfectly without trimming. Haven't ridden in it yet, but it molds to my back and feels comfortable to wear. Hopefully all the air holes will keep it from being too hot. April 19, 2016
Flexible Breathable and Thin Protector is everything that is advertised, it was actually thinner and more flexible than what I was expecting it to be. To me the small size and flexibility make it worth the price. April 14, 2016
Great for AStars GP Plus R Perf jacket Was worried it would add heft to the already tight jacket but it really doesn't. I think the KR-1i would since it has a plastic housing on top of this one. Very flexible which is great as it conforms to your back when tucked. Can't vouch for the protection but judging by the specs it will hold up just fine.Thanks Jeffrey P. for helping me with the decision. April 8, 2016
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