If you need to add a panel-mount connection but don't have the time or ability to cut a custom oval or square hole, this 3.5mm Stereo Round Panel Mount Cable is the easiest and fastest way to panel-ify your project. The adapter is about 30mm in diameter, so you can drill a hole in your wood, plastic, or metal with a common hole-saw or bit, no special shapes or filing required. Un-screw the plastic nut, insert the plug and re-attach. Ta-da! 

It's designed to easily attach to a panel up to ~13mm thick (or 0.5"), or as thin as a few mm. Perfect for connecting audio devices such as smartphones, tablets, MP3 players, car stereos, portable speakers, or any other 3.5mm (otherwise known as "1/8th inch") outputs or inputs. We like this cable particularly for its solid body and 'forgiving' plastic lip that hides the drill hole.