41.8-52mm Bike Headset Base Spacer Crown Race Bike Headset Washer For 28.6mm Straight Fork / 1.5 Tapered Fork Bicycle Parts - Bicycle Headset - AliExpress
Crown CM-311A Headworn Microphone | Sweetwater
AKG/Crown CM311 Headset XLR Microphone | NEW Authorized Dealer | USA 2-Day Ship! 885038024965 | eBay
CM311 MiniXLR | Reference head-worn condenser microphone with mini XLR connector