This kit features the updated style of vice bases for the larger line of GRS® vices, one rubber and one plastic. The rubber base provides more surface friction, allowing the vice to stay stabilized and limiting the amount of movement and tilt. The plastic base is a smoother, harder surface that is great for when you want to tilt and move the vice more freely within the base. These bases fit the GRS Standard Block (#003-530), Low Profile Vice (#003-615), Satellite® Vice (#003-784), MagnaBlock™ (#003-021), and Positioning Vice (#003-541).