Amazon.com : Hycline Single Speed Bike Freewheel, 16T Compatible with 1/2'' x 1/8'' Bicycle Freewheel Threaded Type Freehub Replacement Parts (Black) : Sports & Outdoors
White Industries ENO Single Speed Freewheel 19T [FWSS19T] at BikeTiresDirect
SUNLITE Easy Off Single Speed Freewheel 20t 1/8" – Velo Mine
Amazon.com : ZUKKA Single-Speed Bike Freewheel,16 Teeth Bicycle Flywheel,Compatible 1/2 x 1/8 One-Speed Cycling Replacement Accessory : Sports & Outdoors