Amazon.com: SiYear 3.5mm 1/8 inch TRS Plug to 6.35mm 1/4 inch Jack and 3.5mm Female to 6.35 Male Plug Gold Plated Set Audio Stereo Adapter Converter for Headphone, Microphone (4 -Pack) : Electronics
Brass Adapter, Male (1/8-27 NPT), Female (1/4-18 NPT) – AGS Company Automotive Solutions
Stand/SPUD Adapter 1-1/8" to 5/8" – msegrip
M6x1 (m) to 1/8" NPT (f) Adapter for Grease Fittings – LockNLube
Thread Adaptor 3/8 x 24NF – 1/8 x 27NPT | BrakeConnect
Amazon.com: VCE 1/4" to 1/8" Adapter, 3.5mm 1/8 inch Male to 6.35mm 1/4 inch Female Audio Jack Gold Plated Adapter for Amplifiers, Guitar, Home Theater Devices, Laptop, Headphones - 8 inch : Electronics
LTWFITTING 1/8 in. OD Comp x 1/8 in. FIP Brass Compression Adapter Fitting (5-Pack) HF662205 - The Home Depot