The industry standard for output jacks, and we've got them for mono and stereo applications.
These Switchcraft™ jacks accept standard 1/4" plugs. A mono jack is suitable for most guitars; a stereo jack can be used for stereo wiring, or to enable onboard active electronics when a 1/4" mono plug is inserted. Requires 3/8"-diameter mounting hole; 3/8 x 32 threaded portion is 1/4" long. Mounting nut and flat washer included.