[Kalzazz]

Yes, designed to resist stabs, but also give a fair deal of protection if someone clubbed you in the insert I'd expect

Flexible ballistic inserts are also a thing

Basically the inserts allow the prison to buy one set of expensive inserts which can be used by staff on all the shifts, yet let each officer have his/her own inexpensive vest which they can get their name embroidered on etc and get adjusted just right

The drawback of course is you come on shift and your inserts you get are already wet and warmed up for you by the last shift