As used in the 'Westminster' Electromagnetic Kit (B8A47659) and with coils (B8A47818). Each core is laminated from low loss iron strip to form a roughly rectangular core 90 x 50 x 22mm approximately, with a cross section of 22mm x 12mm, and is cut across the middle to produce two equal C's. A strong spring steel clip is provided to hold the two halves together.