specification:
Product Name: RD-M390 Transmission
Material: aluminum alloy
Weight: 500g
Model: RD-M390
Speed: 9 speed / 27 speed
Colour: Black 
Specifications: Suitable for a variety of tooth change range (28-34T)
Recommended models: commuter mountain bike / folding model
Material: aluminum alloy 
Weight: 270g 
Model: RD-M370 
Speed: 9 speed / 27 speed 
Color: Black 
Suitable for a variety of tooth change range (28 -34T) 
Recommended models: commuter mountain bike / folding model 
