Block N87 Transformer Core, 1200nH, For Use With Choke Converter Topologies, Transmitter

FS-1EFD series size 13/7/4 ferrite transformer cores made from N87. These EFD low profile type ferrite transformer cores are available with air gaps inserted:
Stock number 840-7733 has a 1.0mm gap
Typical applications for these ferrite cores include transformers and inductors in switch mode power supplies

Transformer Ferrite Kits - Cores

The A_L value in the table applies to a core set consisting of two cores without air gap Cores ETD conform to IEC 51(CO)276