Ferrite Toroid, Mix 43, Fair-Rite p/n 2643625002

A relatively small core suited, for example, for an HF QRP balun for portable EFHW antennas.   The relatively high cross sectional area to path length geometry offers potentially higher efficiencies than flatter / higher ID cores.

OD: 0.625" (16.25mm),  ID: 0.311", (7.9mm),  Length 0.562" (14.3mm).  Weight approx 10.3 grams

Balun using a 2643625002 core:  https://owenduffy.net/blog/?p=12642