Stop messing around with little feeble Allen keys to adjust your GBBR! Get a stiffy! The ASP Stiffy knob allows you to quickly adjust your hopup unit without having to take anything apart! Just pull your bolt back, lock it, adjust hopup and your good to go! It will also conveniently fit in Magpul MOE grips!
*If your stiffy last for longer than 4 hours, do not call your doctor. It is working as advertised.*