Are you looking for a LNB or a LNBF? (LNBF has an attached Feedhorn and an LNB bolts to a feedhorn).
C-band or KU-band? C-band LNBs and LNBFs are not usually dual band (high/low) and are typically standard single band with a single LO frequency and no switching.
A hobbyist favorite and proven performer C-band LNBF is the GEOSATpro C2.
If you are looking for a LNB, I will let someone better informed assist.