Wheeler Delta Series AR Upper/Pic Rail Vise Block, 156-888: * Innovative AR vise block is designed to securely hold basically any AR upper receiver * Secures AR-15 uppers by engaging the takedown lugs on the bottom of the receiver * By reversing the direction it will secure most AR-10 style uppers in the same manner * Will secure any pic rail on a hi-rise, standard flat top or many other integrated rail guns by sliding onto and clamping the rail * Durable machined aluminum construction and precise tolerances ensure a secure hold essential for removal and installation of stubborn barrel nuts as well as a variety of other tasks