Compatible with the Real Avid(R) Smart-Fit(R) vise block (not included), the Real Avid Smart-Fit Vise Block Sleeve for AR-10 rifles is a versatile vise block sleeve, designed to convert your AR-15 vise block to an AR-10 block, while eliminating movement and wiggle for safe and reliable cleaning and maintenance. Compatible with most commercial and Mil-Spec receivers, this sleeve can be used with an inverted lower receiver to work on a pistol grip, trigger groups, and other parts and accessories. Simply slide the sleeve over your vise block and adjust the Smart-Fit system to fit securely in your AR-10 magwell and lock the vise block in place.