the frequency range it covers ,but more important than that the preamp
has a much lower noise floor (the MFJs are the worst) than the other
ones and its more stable,some of the others will break into oscillation
in the upper end of the band .Thats just my oppinion after playing
around with the others (except the Palstar ,I havent tried one of them
yet,although its an active antenna not a preselector ) .Thanks