Zup Zilla Nation,
This is my overview of the new Nucleon KR-Ci, CE 1, chest insert from Alpinestars.
Note that most of this overview is compared straight up to the A*’s Bionic chest inserts, which I have in both my Tech-1R and GP Tech Air leather jackets.

Ok, on with it.
First off the packaging is kinda pimp I would have to say. A two sided heavy “zip-lock” type bag that you can reuse for other motorcycle type things.

Sizing:
As you probably already know they come in two sizes, XS-S and M-XL, to best fit the application you are looking for. I currently own both sizes. Why? Well I wear a 48 Eu/ 38 US in just about all Alpinestars(for a “Race Fit”) and have always upgraded my chest pad with the Bionic chest armor. I followed Anthony’s size description and ordered a set of XS-S for jacket size 50EU and under. I got it and found them to be smaller then the stock foam and the Bionic chest inserts. They fit pretty good in the armor pockets, and very comfy, but they moved around more then I wanted them to. Now note, on me and my Alpinestars GP Tech Air jacket, it still covered most of my lowers chest and wrapped around my ribs which was fully covered. I was just so used to more coverage over the upper chest I wanted to know if the M-XL would fit better. Hi-Viz helped me out, with epic service like always, and I got a set of M-XL that fit the armor pocket perfectly. The Nucleon M-XL are the exact same shape and size of the stock foam and the A’s Bionic chest inserts. So if your looking for a straight up swap for the stock chest foam or the Bionic chest the size you will want is the M-XL.

Feel:
They mold to the shape of your body like the OEM foam, but give you the added protection and a new CE1 rating. I think they weight maybe a little less then the Bionic inserts. And there is much more air flow compared to the Bionic chest...I mean it’s like night and day...you have a fan on your bare chest kind of air flow. So if you don’t want to feel it at all and you your 50EU/40US then get the XS-S. If you don’t mind a little bulge and you can kinda feel it then get the M-XL. Both will fit and do the job in your jackets.

Looks:
In my jackets, with the XS-S and a Knox Ageis back protector, you can’t even feel or see it from the outside of the jacket. With the M-XL, you can see a very slight smooth lump from the edges...just thought I would add this if that sort of thing bothers you.

Overall, I really like it. It feels really good and the air flow is great. I used the XS-S pair as replacement hip armor in my A*s V-twin leather pants.

Hope this helps...Ride Safe,
MikeyD

Photo included is of the stock foam and the Nucleon M-XL.

i put it in my Alpinestars T-GP R Air Jacket and it feels kind of loose in the jacket, thought it might have been a tighter fit, still useful, my boobies went up a cup size

I upgraded the chest padding in my AStar Jaws perf jacket with the KR-CI protector. I like how the material molds to your body I can barely notice that it is in my jacket.

These are great. They give me more confidence that if anything happens, I have a bit more protection for what it's worth. And I'll take it. I have three different Alpinestars jackets and I've swapped these out on all of them. I feel these should be standard from AStars instead of the crap foam inserts that come instead.

I am happy I went with the advice somebody else on here gave about going with the MED-XL insert regardless of size chart because that is what the stock size pad was. Fit is very snug inside of my GP Plus R Perf jacket and the high ventilation is very noticeable! What really shines is the level of protection I can feel inside of the jacket when you 'test' the area yourself, yet I forgot it is even there when I am wearing it 10 minutes later. Must have for ANY Alpinestars jacket.

Ordered these in a XS-SM to replace the chest foam in my 2014 GP-R. Slightly smaller than the foam, but definitely more durable. I don't think the size would be an issue, but if you feel like you need that little bit of extra coverage, I would get the next size up. It will still fit.

You can't even feel these in the jacket. Small price to pay for peace of mind.

I purchased these inserts for my 2014 Alpinestars Gunner Jacket. While I have no doubt that the inserts will provide a higher level of protection, they do not fit my jacket well at all. The breast "pocket" holds these inserts in with three tiny pieces of velcro and often releases the inserts when I am in a tuck, taking the jacket off, or putting the jacket on. It is very annoying having to reinstall the inserts at least every other day.

While I am sure they likely work better with newer or higher end Alpinestars, the non-universal (among Alpinestars jackets) fit should be noted. I should not have to sew my jacket for these to fit.

I love this product, have it in my GP Plus R v2 Airflow Jakcet from A-Stars. One thing I will say, I ordered a size 50 jacket, and ordered the small chest protector because the video Revzilla made said that size 50 or smaller jackets require the small chest protector. After getting these in the mail, I realized they were way too small. I checked on the Alpinestars website, and sure enough, the size 50 jacket actually requires the large chest protector. Not a big deal, had to return it and swap out sizes, just be aware that if you wear a size 50 jacket, the sizing Revzilla gives you is incorrect, and you need to go with the bigger size.

Bought theses to upgrade the chest protection in my A* GP Plus R jacket. Ordered the large size and they fit perfectly in the chest pockets of the jacket.

I added the size MD-XL of these chest protector inserts to an Alpinestars T-AST R mesh jacket purchased from a different store. They fit into the chest armor pockets of the size XL jacket okay but the flap feels like it's stretched more than should be needed for the hook/loop of the velcro to attach. Even so, the inserts stay put with no issues. The coverage of the inserts covers down each side of my rib cage down to the edge of my abdomen. Very comfortable to ride with, it doesn't feel like they are there and airflow feels only mildly impacted. This is a great upgrade for Alpinestars jackets designed to work with it.