The single-port 19mm rod clamp mounts on any standard 19mm rod system. A red locking lever tightens the clamp to the rod. This versatile clamp provides 3/8-16 Anti-Twist female accessory mount and 1/4"-20 threads with anti-twist divots, allowing you to mount accessories that feature 3/8"-16 and 1/4"-20 studs with or without anti-twist pins.