Fair-Rite 2643251002 Ferrite bead single 16.75mm hole, 43 material commonly used for RF suppression between 30 and 400MHz.   These are also highly recommended for making very low loss 49:1 transformers that can easily handle up to 100 Watts continuous on FT8, or > 300 Watts SSB.

I highly recommend the excellent Youtube videos by Colin MM0OPX on tests that he has made with EFHW Transformers.

22.2mm L x 39.1mm Dia, ( inside diameter 16.75mm ) For more information see the Fair-rite 2643251002 Data Sheet

Tariff Note:  Brand Fair-Rite USA, Manufacturing Country China, Price increase to Australia due to incresed Tariff