This HDMI Cable Clamp from Niceyrig is compatible with the Sony a7R III/a7 II/a7S II/a7R II camera cage. It attaches to the cage with two 1/4"-20 screws and prevents the HDMI cable from dropping accidentally or braking. It also protects the HDMI port on the camera.
I am using this on a small rig S5 cage to hold the mini HDMI in place. works great. It does get in the way of the LCD screen from opening up, but that's a trade off that is okay with me since I am using a monitor when securing the HDMI in place.
does what it should do. I use it on a smallrig cage for the s5 to hold the HDMI cable. It works well.