The Battle Arms Development Enhanced Pin Set is perfect for adding a little flair to your rifle setup. These takedown pins come in many different colors" allowing you to customize your AR to fit your style. These CNC machined pins fit all AR15/M16/M4 lower receivers with a Mil-Spec .250 diameter. Battle Arms Development" Inc. (B.A.D. Inc.) is a design" research" and development firm incorporated in 2009 with a focus on small arms design including firearm components" tools" gauges" accessories" and complete weapon systems.