Adapt 2.5mm Stereo Plug to Larger Stereo 3.5mm Audio Jack
3.5mm 2 3 4 Pole Mono Stereo Audio Connector Video plug headphone Cable Adapter | eBay
6" 3.5 mm (TRRS) M / (TS) F Powered Mic Adapter
1x 3.5mm Female Stereo to 2.5mm Male Mono Headphones Aux Adapter Converter Cable | eBay
Mono and Stereo (TRS) Cables - the Basics
Amazon.com: Musiclily 6.35mm 1/4 Inch Male Mono Plug to 3.5mm 1/8 Inch Female Audio Mic Professional Headphone Jack Converter Adapter Microphone Accessory, Black(Pack of 4) : Electronics
Parts Express 3.5mm Slim-Plug Stereo Male to 1/4" Mono Male Adapter Cable 6 ft.
3.5mm Stereo Female To 3.5mm Mono Male Adapter #957 - YouTube
Is it OK to insert a stereo jack into a mono plug? Will both channels work correctly? - Quora
Stereo vs Mono Guitar Jacks - Iron Age Guitar Accessories