annodizing, no need for polishing, accepts tank orings, and is fairly light
not a whole lot just it is open face and dirt gets in easier
this blot came with my bl vf and i am highly pleased with its performsnce. just oiled it up a bit and and u r ready to go. nice big air indction hole and accepts tank o-rings so they are easy to replace. i think its a,umin with is decent in weight but heavy compared to the Boss' bolt.
this product comes stock on a lot of guns. worth purchasing no, but if it comes with your gun its great