Generic DSLR 15mm Rod Rail Support Baseplate Mount For Handle Follow Focus 5D2 5D3 GH1 Suitable for dslr cameras,canon 5D2 5D3 etc. This base plate allows you to DSLR cameras The Rails mount height is suitable for gear follow focus to lens gear ring. There is a spacer between knob and clamp, it can protect the knob and clamp from scratch. Screw material: alumimium alloy,Steel. thumb screw, thumb direction can be adjustable.