3.5mm stereo plugs meant for soldering onto cables, you can easily find 3.5mm male to 6.35mm female adapters to bridge different audio connections. These adapters allow a standard 1/8" (3.5mm) stereo port to accept a larger 1/4" (6.35mm) stereo plug, commonly found on professional headphones and instruments.
3.5mm to 6.35mm Adapters
These are typically used to connect professional 1/4" headphones to computers, smartphones, or other devices with a standard 3.5mm jack.