I acquired my Arborist Cinch from Robert Brock in 2016.
The Arborist Cinch is 134 mm. tall, 150 mm. wide, 51 mm. thick, and weighs 587 g. The body is a large aluminum casting with a central slot on the front, a lateral hook on the top (user's) right, two horns on the top left forming a rope groove, two lateral curved horns on the bottom, and a central bottom horn. A cutout on the right side has a nine-toothed steel anvil held in place by two roll pins. On the left is lightly spring-loaded steel lever that actuates an integral eleven-toothed cam. A crescent-shaped plate with two rope retaining horns is attached to the front side of the cam.
The Arborist Cinch comes with a 65 mm. long, 22.5 mm. wide "security extension rope adjuster" consisting of three oval loops of 4 mm. brass. A short brass pin extends out from one side.
The rear of the frame is stamped "PAT. 4546851."
I first learned about the Arborist Switch by reading Robert Wells' article in Nylon Highway #26 (May 1988, pp. 22-23).
The Arborist Cinch is an ascender that can also be used for descent. Arborists often use a double-rope technique that seems strange to many cavers and climbers, but seems to suit their needs. Rather than describe the rigging, I'll refer to the illustration, taken from Robert's article.
The Arborist Cinch is heavy, fairly complex, and climbing with it is not nearly as efficient as with the better caving devices and systems. The cam teeth are sharp, and while it looks strong, the workmanship is fair at best. I doubt that any serious caver would choose it for routine caving use.