Material: zinc alloy+ plastic. Suitable for 4mm banana plug. They have good visibility on the wire connections. You can solder the wires on or just twist them on. 24 K gold plated copper material. Good contact and wear resistance. Good performance under 10000 plug test. They good conductivity, steady signal transmission and good acoustical output. They perfectly the to build a breakout box. Easy to plug and unplug. By turning the rotary button, light force applied, thus laboring and time saving. Well material and offer good products. We focus on every detail and quality products. Durable, mainly use to connect power amplifier stereo. Colour:As Shown Material:Metal Package Contents: 5 x Red binding posts 5 x black binding posts Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.