This vise block allows for safe mounting of the lower receiver into a vise. It is ideal for cleaning , service, or weaponry assembly, and fits into the magazine housing from either the top or bottom. This vise block allows safe mounting of the lower receiver into a vise. Perfect for cleaning , service, or weaponry assembly. Fits into magazine housing from either the top or bottom. Used to prevent damage of your firearm's receiver. Features: Allows safe mounting of the lower receiver into a vise Perfect for cleaning, service, or weapon assembly Fits into magazine housing from either the top or bottom Magazine catch securely locks the receiver to the block Will not distort or damage the receiver Solvent resistant polymer construction