Shimano Tourney Tz500 Tz31 7V 7 Speed Mountain Bike Bicycle Cassette Freewheel Metal Thread Sprocket 14-28/34t Original Parts - China Shimano Bike Parts, Freewheel | Made-in-China.com
Source SHIMANO 6/7V speed bicycle freewheel TZ500-7 Flywheel Mountain Bike Cassette Metal Thread Sprocket 14-28/34T same as MF-TZ21 on m.alibaba.com