AT holding electromagnets are very useful to lock or lift ferromagnetic particulars of any dimension. They work with direct current , as normal permanent magnets.
The electro-permanent type is used when one wants to avoid accidentally triggering the device in the event of a power failure.
Moreover, Calamit creates electromagnets in c.a. (EM) o c.c. (PM), in both traction and thrust, with forces ranging from a few grams to 400 Kg.