SureGrip300 BFA/Banana (Gold). Beryllium-Copper is stronger, more conductive, and better sounding than normal phosphor-bronze connectors. Direct-Gold Plating, no distortion causing nickel underneath. Cold-Weld System for an ideal connection, better sounding than solder: Tighten Allen-screws with supplied tool to create an ideal connection between plug and conductor, then slide the no-magnetic-interference ABS casing over the banana screw into place. Fits up to 9 AWG speaker cables.