... :P504A-BV1.0/1.2 P means plastic feed frame,casting feed frame without "P"504 is the code for wire feed ... frame we have 21,401,402,404,501,502,504,P504 ... type of roll ,we have V,U,K,Three types,"V"fit to steel wire ,"U"fit to fluxcore wire an "K ... .0/2.4the drawing of the P504A: Plastic casting feed frame