SmallRig Long Lens Carry Handle(Rubber)1701 - YouTube
Found Handle for Sigma 150-600C (and similar long lenses): Third Party Lens Talk Forum: Digital Photography Review
Amazon.com: Universal Ergonomic DSLR Mirrorless Camera Camcorder Monocular Hand Grip Stabilizer, Portable Handheld Selfie Stick, Long Focus Lens Video Light Holder Mount for YouTube Tiktok Vlogging Starter Kit : Electronics
2 X Slr Camera Lens Focusing Handle Focus / Zoom Ring Lever Quick Focus - Lens Adapter - AliExpress
SmallRig Camera Long Lens Handle 1732
2 X Slr Camera Lens Focusing Handle Focus / Zoom Ring Lever Quick Focus - Lens Adapter - AliExpress