DQITJ 2 Pcs Single Speed Bike Freewheel, 18T Compatible with 1/2 x 1/8 One-Speed Cycling Replacement Parts Production Description: 1: TEETH: 18T, Chain compatibility: 1/2" x1 / 8", 2 pcs included. 2: SIZE: The inner diameter: 1.34 inch (34.1mm). 3: MATERIAL: Made of high tensile steel material, high precision, smooth rotation and easy maintenance. ..