Compatible Equipment Type: Excavator. Material 50Mn, through hardened HRC 25-28, CASE hardened HRC52-56, hardened thickness 5-8mm. Yield strength? 0.2 (MPa):? 310. Roller, 45# carbon steel or 40Cr, quenched HRC25-30, surface quenched HRC52-58, hardened to a depth of 2-3mm. Bolt, grade 12.9, HRC45-52. This bottom roller is a durable undercarriage replacement part for your excavator. Our rollers utilize special high strength-hardened steel and quality seal groups that provide excellent lubricating oil retention. Sealed bearings stop dirt, mud, and grime from penetrating inner components. It was designed and manufactured to exact OEM specifications using a high-quality, high-strength steel. It will provide long-lasting and dependable performance even if you operate in the most extreme conditions. Please make sure it will fit your machine before purchasing it. If you are not 100% sure this is what you need, please find out your engine model, series number and contact our Customer-service. Communication is the best way to solve the problem. If you have any problems after you. Please keep in mind that spending time before purchasing the part to confirm it is indeed exactly what you need can help prevent you from ordering the wrong part. Replace/return are available if buyers receive wrong/damaged/defective items. Anyway, by nice communications, we can find a way to make you satisfied. Very appreciated for your support. Feedback is very important to us. Feedback, so that we can satisfactorily address your concerns. We will do our best to solve your problem as soon as possible.