Ergo Grip, MAST, Modular Armorer Stand, For Large Frame Glocks, Includes Base, Black NEW MAST design allows each module to be mounted in a vise, screwed to a work bench, or secured in the base Made from reinforced polymer The MAST base comes with two stainless steel pins for securing each module MAST base has four mounting holes & allows the base to be screwed to any flat surface MAST modules lock securely into the firearm's existing ambi-magazine release Product Description ERGO's MAST is one of the most useful maintenance accessories available. Simply bolt, clamp, or slide the MAST modules into the MAST Base to securely attach it to a bench. Then slide your firearm onto the module to lock it in place.