These are one piece extruded aluminum heat sinks that were recovered from industrial motor drives. They have internal slots for PCB mounting so originally they served as both the product housing and the heat sink for seven power devices. With some creative imagination you may be able to use this feature in your design for a unique and distinctive looking project. The red color is the anodized aluminum finish and not simply paint, so it is very durable. They measure 4.25” L x 4.75” W x 3.5” H and weigh 1.5 pounds each. The PCB slot holds a board 0.060” thick and up to 4.25” x 3.25”. They have 7 holes in the walls, 4 tapped holes in the base, 2 tapped holes in one end, and 6 slots on the mounting flanges. Thermally, I would estimate each heat sink would easily handle a 150W AB amplifier channel. These are in very good condition with just a few small scratches and have been cleaned free of thermal grease. Buyer to pay FedEx ground shipping on the 4 pound box. Thanks.