The SIRUI PH-180 Quick Release Plate (ARCA-compatible) made for Sirui Gimbal Heads, PH-20 and PH-30 gives you better possibillity to fix the lens in the right position to make it "weightless"
Two screws (1/4" and 3/8") to insure proper alignment and maximum security. A rear ridge helps preventing the lens from turning if only one screw is used.
Stop screws on the bottom of the QR plate, prevent your lens and camera from accidentally sliding off the head when the Quick Release Clamp is loosened.