The Joule's Insert can be placed into a standard calorimeter cup 50 x 75mm (D x H) to make a Joule's calorimeter. The Joule's Insert consists of a calorimeter lid, complete with stirrer, with 2x 4mm spin free socket head terminals supporting conducting rods that carry a 2 ohm resistance heating coil. When fitted to a calorimeter cup, a certain weight of water can be heated a certain number of degrees and the electrical energy required to do this can be accurately measured. This is often used with the Insulating Box & Lid 0830-001.