... ,casting feed frame without "P"504 is the code for wire feed frame we have 21,401,402,404,501,502 ... V,U,K,Three types,"V"fit to steel wire ,"U"fit to fluxcore wire an "K"fit to aluminium wire0.8/1.0 is ... ,The feed -roll dimension can change it for your welding wire size. Our standard feed-roll size:0.6/0.8 ...