Panel Mount 1/8 / 3.5mm Mono Connector : ID 4361 : $0.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Mono-to-Stereo Adapter Corrects Missing Sound from 1 Side
Goobay Audio Jack 2-Pin Male 3.5 Mm Mono Connector Black| Techinn
Amazon.com: 3.5mm Female Connector Mono Jack 1/8" Inch w/Strain Relief Back Audio Phone Solder Terminal Metal Threaded Insert Black Plastic Handle 3.5 mm Mono Audio Phone Jack : Electronics
Amazon.com: Monoprice 107128 3.5mm Mono Plug to 3.5mm Stereo Jack Adaptor, Gold Plated : Everything Else
Mono and Stereo (TRS) Cables - the Basics
1/4" Audio Jack - Mono Enclosed - Griffin Effects
Premium 3.5mm (1/8 Inch) TRS to XLR Male to Male Mono Microphone Adapter Cable (6FT) - 3.5mm Male to XLR Female, XLR to Auxiliary AUX Headphone Audio Jack Plug Converter Wire Cord -
3.5mm Right Angle MONO Audio Jack
Williams Sound 1/8" Stereo Jack to 1/8" Mono Plug Adapter ADP
Is it OK to insert a stereo jack into a mono plug? Will both channels work correctly? - Quora