YHM's line of sRx products were designed with aesthetics and ease-of-use as the top priorities, and that is no different for the YHM sRx Q.D. Adapter (YHM-4400). This Low Profile, Q.D. Adapter/Mounting Interface attaches to the industry standard (HUB) 1-3/8,x24 threads. It features an internal taper seal-in front of the threads-that locks your suppressor on and forms a tight seal to contain gasses while in-use. This means no gasses or debris can build up on the threads.