Hi,
Does anyone know what the little round donut shaped thing on the wires of a speed controller are called and what they are for? I have 2 align controllers, 1 with and 1 without. Are they needed and if so where can I get a replacement? Thanks

Ferrite ring, it blocks some spurrious interference signals from causing glitching to your radio. More critical if you use 72MHz.

Thanks, I'm using 2.4 so hopefully I'll be safe.