The 4mm aperture securely holds a 4mm banana plug in place, or the 4mm cross hole allows for bare audio /speaker wire to be securely locked in place.
2x Brass Gold Plated Right Angled Banana Plugs 4mm PREMIUM QUALITY Amp Speaker
HDSupply High Speed HDMI Cable with Ethernet HDMI A Male (19-Pin) to HDMI A Male 19-Pin 2x Shielded Gold-Plated Contacts
Pro Gold Plated 2x Phono to 2x Phono Audio RCA Leads cable 0.5m 1m 1.8m 2m 4m 5m
2x Phono RCA Splitter Gold Plated Y Adaptor 1 Male Plug to 2 Female Sockets
2x Gold Plated RCA Phono Coupler Female to Female Adapter Extender Audiophile 2
2x Speaker Cables With Gold Plated Banana Plugs Both Ends. 2.5mm Thick 5m Long
