This is a 75 to 300 ohm matching transformer balun used to connect your 75 ohm cable to your 300 ohm TV antenna terminals. 5 to 900 Mhz, covers UHF, VHF, and FM. Overall length is 4 inches. (The body is about 1-3/4 inches including the F port, with the leads being about 2 1/4 inches including the spade ends.) For indoor use only.