The IEC Joule's Insert can be placed into a standard calorimeter cup 50x75mm DxH 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 IEC 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 IEC Insulating Box & Lid (HL0830-001).