Ferrite Core - Cylindrical - 300 MHz - 1.2 mm Length - 1 mm ID - 2.5mm OD. The UECB200L250000 is a Bead Core suitable for use on round cable. The EMI cores are part of a family of passive components which address the issues of noise or electromagnetic interference (EMI) in circuits or systems. When the desired performance of an EMI core cannot be obtained with a single pass through the core, the impedance characteristics can be changed with multiple turns. A turn is counted by the number of lead-wire windings which pass through the inner hole of the core. Adding turns will result in higher impedance while also lowering the effective frequency range. Product Highlights