Primos Heavy Optics Adapter - The magnetic attachment system gives instant fitting and has an adjustable lever system for extra security. Lightweight and durable, the Heavy Duty Optics Adapter comes with a standard 1/4"-20 camera/optic screw, 3/8"-16 bushing and polymer plate. Turns your APEX MagnaSwitch Head into a super stable optics and camera platform in seconds Designed to attach to cameras and other optics with standard 3/8"-16 or 1/4"-20 threaded female mounting points