This is the first time I've run across on of these, and I'm not sure why. It's really an ingenious device, utilizing a wedge to instantly secure a board for jointing. Three screws are used to mount it to a bench top (or a board that can be clamped to the top). The board is held in place by a hook and the wedging forge generated by pushing against the board. The harder you push, the tighter it grips. The board is removed by pulling backwards. Grips a board from 0-2 1/2" thick. The minimum height of the board should be 1" to clear the sides. 11" long overall. If I wasn't left handed, I would keep this for myself (you could mount it for left handed use, but it just doesn't look right that way). Made from sturdy cast aluminum.