SKF NATR 17 Yoke Type Track Roller, Needle Bearing Type, Crowned Roller, Unsealed, Metric, 17mm Bore, 40mm OD, 21mm Width Track roller with needle bearings supports high static and dynamic loads in track-type applications Crowned outer ring for resistance to misalignment Yoke-type rollers for use with heavier loads or where clevis mounting is preferred Thick outer ring helps minimize deformation under bending stresses Unsealed for applications where contamination is not a factor