it adopts high intensive but low extension chemical libre string as skeleton. which is covered polyurethane pouring glue on both upperand below surfaces. Its double surfaces (or single surface) are arc. It has various advantages of all resistance wear resistance, shock suppression and small noise, It is many applicable to driving household electric sewing machine ,highspeed table drill,washer as well varous precision instrument. we are able to produce according to user’s requirements for diffenerent circumference and model.