CowboyStudio FOTGA DP500 Follow Focus FF for DSLR 15mm Rod and Gear Ring Belt For Canon Nikon One (1) FOTGA DP500 Follow Focus, One (1) Matching Gear Belt Fit Rail Distance: 60 mm, Fit Rail Diameter: 15 mm Gears Nylon and ABS Dial Index Adjustment: 360 Mounts onto 15 mm Rod Support (60mm center to center difference). Compatible with industry standard 15mm rods