Tier trap filter to block a small band to enable one or two channels with own content (channel S30 & S31). The HSF 374 blocks the frequency range of 354 up to 412 MHz to make frequencies 374-390 MHz free for other use. The blocked frequency range is in the DOCSIS band of Ziggo (former UPC regions). This means the filter blocks a part of the internettraffic of Ziggo. We recommend to use two HSF 374 in a row to ensure the best result. See the wiring diagram for the correct installation. Also available in a version with other usable channels (channel S16 & S17) with a blocked frequency range in the DOCSIS band of the former Ziggo regions (HSF 265; article number 695004728).