Anderson Power Products SB50 Connector Kit, 50 Amps, Red Housing, w/ 6 AWG Contact AWG Contact, 6331G1 (1 Pair)

What size solder slug can I use ?

are these available for 4 gauge wire?

Are these a mating pair of connectors, or both male plug ends? I am looking for a set of male plugs to fit Anderson flush mount plug bases.