A little lexan reticle levelling tool, simple, basic.. Pretty much just a piece of lexan that sits on the bolt raceways, comes out, does a 90 degree turn, with a vertical black line on the upright. Quick easy and simple enough for a hillbilly like me to get a reticle sorta square.

I may have the name of it written down somewhere, but for the life of me I can,t remember what they,re called, who makes them or sells them.

If anybody could point me in the right direction, it would be greatly appreciated!!..