This durable, multi-purpose and essential tool clamps into a bench vise, so that you can then slide the lower receiver magazine well down onto the upper portion. This provides a stable platform to perform a variety of repairs or installations on the AR lower receiver. CNC cut NO-MAR® polymer construction protects your receiver’s finish. Multi-Lock® feature locks receiver in any position – install through top or bottom of Magazine Well. Works with the Upper Receiver installed or removed, and provides access to trigger guard, pistol grip & buffer tube to make trigger & safety installations much easier. Works in any size bench vise, and the built in support puts no strain on your magazine release. Universal fit works with any AR15 lower receiver. Made in USA.