Miter clamps are designed to hold miter joints together. The earliest miter clamps are a simple spring in a C-shape with sharpened points that are sprung onto the outside corner of the miter joint. The right angled plates are higher than the screws and the red holder. The screws go under the frame (work-piece) to be held, and the red bit clamps down on the lower-edge of the frame. Recent designs are more complicated; a rigid body holds one fixed and one moveable jaw activated by a cam. Examples of the newer clamps are Jim Chestnut's "Clam Clamp" and the Maestro Miter Clamp.