BOYA BY MP4 Microphones 2 channel Audio Adapter with a 3.5mm TRRS cable and 3.5mm TRS cable Designed for Smartphone, DSLR Camera (1pcs) Instrument (Professional) Cables - Newegg.com
BOYA BY-WM4 Pro K1 K2 wireless Lavalier Microphone System BY-MP4 Audio adapter | eBay
BOYA BY MP4 Microphones 2 channel Audio Adapter with a 3.5mm TRRS cable and 3.5mm TRS cable Designed for Smartphone, DSLR Camera (1pcs) Instrument (Professional) Cables - Newegg.com
Boya BY-MP4 Audio Adaptor for Smartphones & DSLR Camera Overview - YouTube