Sennheiser Inflight-Adapter - - Inflight-adapter (3,5 mm double mono-plug)
BINYOU 3.5mm Headphone Adapter Jack Plug Converter For Audio-Technica ATH-M70X M40X M50X M60X For Sennheiser HD518 HD598 HD599 - Walmart.com
Amazon.com: EPOS | Sennheiser Adapt 165 USB II (1000916) - Wired, Double-Sided Headset - 3.5mm Jack and USB Connectivity - UC Optimized - Superior Stereo Sound - Enhanced Comfort - Call Control - Black : Electronics
3.5mm Headphone Adapter Jack Plug Converter | Audio-technica M50x | M50x Jack Adapter - Protective Sleeve - Aliexpress
9V AC Adapter for Sennheiser TR120 Wireless Headphone Transmitter Power Supply | eBay