... the type of roll ,we have 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 trough dimension of roll ,Unit ... for you,The feed -roll dimension can change it for your welding wire size. Our standard feed-roll size:0.6/0.8 ... ,0.8/0.9,0.8/1.0,1.0/1.2,1.2/1.6,1 ...