The basic principle of the holding or pot magnet is to direct and concentrate the flux from both magnetic poles to one active face. This is usually achieved with steel pole pieces or a steel-backing cup. Pot magnets are made predominately made from three types of magnetic material

1. Sintered Ferrite this material is inexpensive yet offers good performance. The steel parts are plated and the ferrite is inert so give good resistance to corrosion. The maximum operating temperature would be +120 °C
2. Cast Alcomax is a more expensive material but has a greater holding force than ferrite, and can be heated to extreme temperatures of between +120°C up to a maximum of +500°C.
3. Rare Earth Samarium & Neodymium, pots and assemblies can offer up to eleven times the performance of a Ferrite system in a comparable size. Applications tend to be specialised engineering projects where performance and available space are key factors. Maximum operating temperatures are +60°C for the Neodymium and +150°C - +250°C for the Samarium depending on the design configuration.