3.5mm Stereo Jack to 3.5mm Mono Plug Adapter - HamiltonBuhl
Amazon.com: Monoprice 107129 3.5mm Stereo Plug to 3.5mm Mono Jack Adaptor, Gold Plated : Electronics
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1pcs 3.5mm Audio Mono Stereo Male Jack Plug 3.5 Mm 2pole 3pole 4pole Right Angle Plugs For Phone Headset - Connectors - AliExpress
Vanco International | Right Angle 3.5 mm Mono Plug - Stereo Jack Adapter