Precision focusing through a 110mm range Index Scale on both sides 48mm diameter metal thumbwheel with 1/4 inch-20 Screw. Arca/ RRS compatible 55mm dovetail plate w 1/4 inch-20 threaded socket. Helping to achieve exacting camera-to-subject distance, the Macro Focusing Rail is a focusing stage offering fine- tuned control across a 115mm adjustment range The Rail is driven by a knob-controlled worm gear and index scales, in millimeters, are printed on both sides of the rail for consistency.. Cameras can be mounted on top of the rail via the integrated 1/4 inch screw, which uses a 48mm-diameter thumbwheel to secure cameras in place. 214mm overall length (including adjustment knob). Weight 293g (10.3oz). Package List: 1 * Rail Slider Plate Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. .