... roller bearing, We product:heavy duty needle roller bearing without inner ring:NK, NKS, RNA49, RNA69.heavy duty needle ... GCr15 bearing steel, quench-hardening HRC60---65.Material for inner and outer races is GCr15 bearing steel, quench-hardening HRC61--- ... or reinforced nylon.Special Directions:Bearing running clearance and inner-cutting roundness should be regulated according to different conditions ...