NOTE:This rail only support for our server case, please know it before you order it. 1. Heavy-Duty Slide Ball Bearing Rail for 2U 3U 4U server case 2. With stop-latch, lock chassis in extended position for easy access 3. Lock-open to secure the chassis in position for easy access, more tapped screw holes on outer member, easy-mount, quick-disconnect design. 4. Supports 3U, 3U, and 4U Equipment 5. Adjustable rails