Body-Solid Linear Bearing Smith Machine has linear shafts that are case hardened solid steel with a surface hardness greater than HRC60 for the highest load capacity and the lowest coefficient of friction. The linear motion bearings ensure a precise, smooth linear motion system that endures high vibrational loads and shock loads without play. 28 Lock-out points are spaced 2-1/2 inch apart for convenient start and stop positions. Heavy-duty adjustable satires for user safety.