ZF41003TC is an epoxy coated toroidal core in Magnetics F material

Magnetics F material is a medium frequency general-purpose ferrite material. Engineered for lowest losses at 60°C

Ferrite toroids offer high magnetic efficiency as there is no air gap, and the cross sectional area is uniform.

Epoxy is coated to 200C continuous operation. Coating thisckness with Epoxy is typically less than with Nylon