Bolex produced a wide ranging array of handgrips for its cameras. The very first handgrips they made were for the round base models and it was one of the most needed accessories when it first came out.
The first handgrips were extremely well built being often made of just a solid block of metal.
Later handgrips were still as well built but tried to do the job using less weight and tried to make the method of attaching it to the cameras easier.
They also had functionality built in to start the camera running and control some of the lenses.