1.low noise,low libration 2.seals type:open,seal,shield 3.high-end technology ... 1.Low coefficient of product,reduce tire damage 2.Running smoothly and durable.3.Poduct size ... stainless steel,iron,copper,ect.2.Sealing from:2RS ZZ ,Z ,RS,OPEN (metal or nylon)Product Series ... industry's most comprehensive category of manufacturing enterprises. 2, We have nine years experience in manufacturing bearings ...