Zhong Yi Optics B4 to M4/3 2X Extender - Newsshooter
Lens Adapter For Fujinon B4 2/3" Lens to for Panasonic GH5 Micro 4/3 Camera | eBay
Cheap B4 Zoom Lenses for Micro 4/3" Cameras - YouTube
Anyone else rockin' a B4 lens on their GH5? : r/videography
GH5s + B4 lens = The Unbeatable setup
Amazon.com : B4 2/3" 12-Pin to DC 12v Power Cable for Fujinon, Nikon, Canon, Angenieux, Schneider Lens Servo Having a Cable with a Hirose Style 12 Pin Male end : Electronics