Set of 6 Heavy Duty CVT Pulleys 18mm x 14mm These high quality HD [Heavy Duty] polymer CVT pulleys not only provide excellent durability as a replacement for worn out original rollers, they also offer upgrades to ensure the CVT operates to its full potential. The inner race is knurled during production to ensure that the HD polymer outer race remains in place even under the most demanding conditions. The high proportion of PTFE (polytetrafluoroethylene) in the outer shell ensures good self-lubrication and therefore a long service life. The sliding properties of PTFE also ensure easy movement during operation. Excellent quality and value for money, and one of the most durable CVT pulleys on the market.