AR15 Lower Receiver Vise Block allows you to mount a MIL-Spec AR15 receiver to the vise block, for securing the AR lower receiver to a bench vise for maintenance and assembly. Includes a removable buffer tube mount ring to aid in installing carbine buffer tube straight and plumb onto the receiver. It will hold and lock the carbine buffer tube in place, so that the castle nut can be properly tightened without misaligning the buffer tube. Includes: AR15 lower receiver vise block, Buffer tube support ring with three thumb screws, Pistol grip bolt for securing receiver to the vise block