It's aluminum alloy screws for bike, used to replace the old bike plastic screws. It fit birdy2, 3, Ti, P40, GT, CITY, R20, CLASSIC and other series can be used, and beautiful. , . Front fork: Use 2 M5X18 screws to fix the front wheel when folded. Derailleur cable: Use 1 M5X18 screw to block the derailleur cable. Rear fork: Use 2 M6X18 screws to adjust the fixation of the rear wheel when folded. Name: Aluminum alloy screw for Weight: M5X18: 5 grams [including nuts] M6X18: 6 grams [including nuts] color:Gold Material:Aluminum alloy Package Contents: 3 x M5X18 Screws 2 x M6X18 Screws Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.