I have a Sears professional series I got on a catalog sale. It has Miller stamped all over it and appears to be the same as a Millermatic 251. Right now it has a 40 pound spool on it and the rollers have no problem starting / stopping the wire / spool. It does great on up to 1/2 inch steel so far with .035 wire. Makes a nice clean weld with very little spatter on axle housing / spring perches. Next project is to try it on some body sheet metal, but I have been told I should downsize on the wire. I am very happy with it - like a compressor, a little more money spent here is worth every penny when you are trying to do a good job and make good use of your time down the road.