Direct Broadcast Satellite (DBS) dishes use an LNBF (“LNB feedhorn”), which integrates the antenna’s feedhorn with the LNB. In the case of DBS, the voltage supplied by the receiver to the LNB determines the polarisation setting. With multi-TV systems, a Twin LNB allows both to be selected at once by a switch, which acts as a distribution amplifier. The amplifier then passes the proper signal to each receiver according to what voltage each has selected. LNBFs should never be used on Prime Focus dishes, this always results in extremely poor performance.