Mueller Electric’s BU-3110410-x are fully insulated, stackable, 4 mm banana plugs intended to be used with CoolFlex45 10 AWG wiring. These banana plugs can be plugged into any standard 4 mm banana jack that accepts shrouded banana plugs. The jack end will accept any shrouded, unshrouded, or retractable 4 mm banana. The banana plug has a plastic safety tip.