Basically a split high permeability ferrite core with a plastic case, these devices are ideal where parasitic voltage spikes are a problem or potential problem. The cores come in a hinged plastic case, simply snap on to the computer or data cable. Three versions are offered which cover most computer leads etc.MODEL U16:A compact attenuator that will pass a cable up to 8mm dia (most monitor cables etc). Typical impedance at 25MHz 300ohms approx, 590ohms at 100MHz dropping off after that. Case measures: 20Lx19Dia mm.- Pack 4