Ferrite Bead for lower frequency (< 50MHz)  EMI suppression.

Typically used in multiple bead strings on SMPS DC leads or thinner coaxial cable.

Examples:

Multiple bead RF choke for  RG58 or RG303 coax (W2DU choke balun)

Example SMPS EMC Reduction (Samlex Power Supply)

FB-73-2401 = Fair-Rite 2673002401 (superceded by 2673002402)