Hand Screws

A hand screw clamp uses two wooden jaws, each riding on its own independent screw, so the jaws can be angled non-parallel to grip a tapered leg, an irregular assembly, or anything else that isn't two flat, parallel faces -- exactly the case a flat-jawed metal clamp handles badly. The wide wooden jaw faces also spread pressure across enough surface area not to bruise or dent softer material the way a narrow metal jaw can.

Setting one takes longer than closing an F-clamp or C-clamp -- both screws need adjusting to get the jaws parallel to whatever odd shape they're gripping -- which is exactly why hand screws stay a specialty tool for irregular work rather than a general glue-up clamp.