Features:1. The portable size makes it easy to carry along.2. The retractable spring could do a great job.3. This ball shape spring lock comes with delicate workmanship.4. Made of ABS, it is sturdy and durable5. A good accessory for indoor cycling bikes.Specification:Material: Steel and ABSColor: Black and YellowScrew Diameter: M16 x 1.5Screw Length: 20mm/0.79"Shaft Length: 12mm/0.50"Total Length: 81mm/3.22“Shaft Diameter: 8mm/0.31"Max Diameter: 49mm/1.93"Package Included:2pcs x Pull Pin Spring Knob