A large ferrite core suitable for reducing RF on power supply lines in RF amplifiers. Simply wind a few turns of the positive power supply line through the core to prevent RF getting back the power supply and affecting regulation.
Manufactured by Laird, part number 28B1020-100
Size: 28.6 (L) x 25.9 (OD) x 12.8 (ID)mm
Impedance at 100MHz is 276 ohms.