Constructed of black injection molded polymer.Fits both carry handles & flattop uppers. Easy to use, the block lets you tightly clamp a carry handle receiver or flattop receiver in a large bench vise. The vise block is locked into the users table/workbench vise. Holds the rifle firm so you can work on your rifle securely without scratching or damaging the finish for effective cleaning, assembly, and repair. Made In the USA