The XS AR Upper Receiver Block is designed to allow the user to hold an AR-15/M4, AR-10, SR-25 or DPMS GII upper receiver in a bench mounted vise for assembly, modification and maintenance.
This upper receiver armorer's block will allow the gunsmith or enthusiast to assemble, modify, or maintain almost every AR pattern modern sporting rifle. While most blocks will only fit one specific style, the XS block provides the versatility need to work on any AR pattern upper receiver: AR-15, AR-10, SR25, or DMPS GII. This versatility, plus the reliability of an XS Sights Made in the USA 6061 T6 aluminum product, is a one size fits all solution.
Will not work for ARs in .300 Win Mag or 12 ga.
Link to XS written Installation Instructions
WARNING Cancer and Reproductive Harm – www.P65Warnings.ca.gov