M5 17mm maintenance thumb screw knob for rod clamp rail block DSLR photography.It is spring loaded, and can be pulled out and turned to a more user friendly position after being tightened.Made of aluminum alloy, durable in use.T-shaped Design: Convenient and comfortable adjustment.You will not need spanner with wrench csrew when you fix your device.Specification: Material: Aluminum AlloySize: Approx. 3.8 × 3cm/1.50 × 1.18inchPackage Includes: 1 Piece T-Shaped Handle