SUNWAYFOTO brand Arca-Swiss / RRS compatible Multi-Purpose Rail DPG-2416R with Double Arca Dovetails. Precision CNC machined nodal slide. Compatible with all Arca-swiss style quick-release plates. Accurately find nodal point for panoramic photography. For close-up photography, slide the camera in and out without moving the tripod. Double Dovetail allows you to mount the rail to an arca clamp and combine with the bi-directional clamp for incredible versatility. Width: 39mm. Length: 240mm. Height: 16mm. Weight: 194g. Mounting hole: 1/4-20″. 1. Precision machined from solid aircraft-grade aluminum. 2. Hard -anodized finish, durable and resists scratches. 3. Sliding backstop to secure long lenses. 4. Easy-recognized laser-engraved scale on both sides of the rail to adjust the nodal point conveniently and accurately. 5. Safety stop screws included. All metal construction. Includes allen wrench 2 stop screws and 1/4" cap hex screw.