Opteka 47-inch All Metal Track Dolly Slider Video Stabilization Rail System for Digital SLR and Video Cameras Full length, lightweight camera slider for smooth left, right, forward, backward and slanted glides Removable sliding carriage with 1/4" and 3/8" screws for attaching a camera or fluid head Supports rigs of up to 11 lbs; Bubble level for measuring evenness Three 1/4" and three 3/8" threads along the bottom for mounting a tripod Removable feet with rubber tips that provide a secure grip