No. 31-335 Sander/Grinder consists of the 31-330 machine, 49-103 V-belt, 5250 pulley, Base and Standard Duty Single Motor. The machine is completely and ready to plug in on 115 V, 60 cycle, single phase . No. 31-356 Sander/Grinder is the same as the 31-355 unit with the exception that the three phase motor is Available as accessories for I ...