rails allow smooth 4- movements from left to right or front to back. Screw knobs allow you to adjust finely along the scale and find accurate camera positions for taking macro photography, close-ups, and time-lapse videos. yet , this black anodized focusing rail boasts a load capacity of 5.5lb (2.5kg) while weighing only 1.3lb (570g) for easy portability. The quick release plate can promptly attach your camera to the rail and secure it with the clamp. The 1 or 4inch-20 screw is compatible with for DLSR cameras and more. Mount the focusing rail to a tripod with the 1 or 4inch-20 screw or an Arca-compatible video head for stable supports and angle adjustments. Different factory batches, if there are slight differences, it not affect the use of the product Quick Release Plate: Compatible with Arca Colour:Black Material:Aluminum Alloy Package Contents: 1 x Macro Focusing Rail Slider Only the above package content, other products are not included. Note: Light reflection 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.