Provides additional parking braking force when parking or starting on a steep slope. For SURRON For Surron For Sur-Ron For Ultrabee For Ultra-Bee. The internal bearings are smooth, providing a delicate operating feel without any sticking. The dual-safety braking system greatly enhances the sense of security while riding. Surface treatment can improve hardness,stable performance,anti-rust,durable,light weight., Manufacturer: MOMOHCHGBT