Jobu Design Heavy Duty Black Widow Gimbal, with Arca-Swiss Style Quick Release Base, Requires Mounting Plate.

If your lens arsenal contains a monster-sized, back-breaking heavy lens then you need a support that is up to the task of holding it properly and safely without adding a lot more weight to your backpack. Jobu Design's Heavy Duty BWG mounts your 400mm F2.8, 500mm F4, 600mm F4 or 300-800mm lens quickly and securely.

By re-orienting the mounting clamp to a horizontal position (rather than vertical sidemount) you allow a much easier way of installing the lens, and you remove all the shear stress from the lens-collar on your telephoto lens.