The lightweight Professional Camera Cage Kit from SmallRig provides accessory mounting and protection for your a7S III mirrorless camera, and it includes an HDMI cable clamp and a wooden side handgrip.
The camera mounts onto this formfitting aluminum cage with an integrated 1/4″-20 screw, and it features multiple 1/4″-20 and 3/8″-16 accessory threads, ARRI-style accessory threads, a NATO rail, a shoe mount, strap slots, and front threads for a separately available lens adapter.