Needle roller bearings without inner ring includes NK、NKS、RNA48、RNA49、RNA69、RNAO series.The rolling needles roll directly on the quenched and ground shaft. The needle bearings without inner ring  are compact in structure. The rotating precision will be increased if the shaft is machined with high precision. For those needle bearings without retaining edge or inner ring (RNAO),the outer ring and needle unit can not be exchanged