The Sony a7S iii fits well and follows some of the tenets (small anti-curl screen) of the a7 iii platform. BUT it missed out on one of the key benefits of the a7 iii setup when it comes to fitting the Peak Design clutch handle. The lower rail for attaching the clutch handle is not present on the 7S iii. There is also a clip for an HDMI cable. Pretty bulky and heavy. Need a few more tweaks on this rig to make it into the A7 III class.