MFJ-270 Lightning arrester DC-1GHz, UHF-F/F 400W by MFJ handles up to 400 Watts PEP. Has SO-239 connectors and works with all types of coax fed antennas. lightning surge protector safeguards your ham radio equipment from damaging static electricity and lightning induced surge arrest traveling on coax feedlines. MFJ-270 presents a constant 50 Ohm impedance to your transmission line. insertion loss of less than 0.1dB. It can be used up to 1000 MHz.