I am trying to locate information about three wood clamps similar to the one in the attached photo. They seem to be made from solid blocks of maple. In all cases, the screws are about 15” long. The overall width of the clamps differs in turn: 23”, 25.5” and 28.5”. That means the interior maximum size is about 18”x 8”, 21”x 8” and 24”x 8”. While they look to be in rather new condition, they do not have any manufacturer’s name on them and their “style” seems antiquated. Would you be able to shed some light on what their origin might be? Thank you for your consideration and assistance