Amazon.com: 3.5mm Stereo Male to Dual 3.5mm Mono Male Audio Cable, 1ft 3.5mm 1/8" TRS Male to 2 x 3.5mm 1/8" TS Male Y Breakout Cable Splitter Adapter for Headphone, Speaker :
SAF-SA25M - 2.5mm Male Plug to 3.5mm Female Jack Stereo Audio Headphone Adapter
Adapt 2.5mm Stereo Plug to Larger Stereo 3.5mm Audio Jack
10pcs 3.5mm Audio Jack Pcb Mount Screw Metal Nuts Mono Stereo Phone Plug 2 3 4 Pole Connector Through Hole Panel Mount Thread - Connectors - AliExpress