One truth about working with audio is you always need the cable or adapter you don't have in your toolbox. That's why we love these terminal-block audio connectors so much. No soldering required! Use stranded or solid core wire and a small screw driver to create custom wiring jigs.
This is the 3.5mm (1/8") 4-Pole (TRRS) Audio Jack Terminal Block. TRRS stands for Tip, Ring, Ring, Sleeve. It has four total pins - three signal and a ground as opposed to a more common stereo jack's three. This type of connector is most often used in smartphones & cellphones to provide stereo audio and one mic channel.
Note that the green block labels it as GND-blank-Right-Left which is the most commonly used order. However, it would be more technically correct to just label it Sleeve-Ring-Ring-Tip: goes in the same order as the four contacts on the plug.
Note: As of Tuesday, April 12th 2016, this product is now gold plated instead of nickel plated.