Models BWL-9050 & BWH-9060 (BWH-BWLQ-R) are extremely sharp cut-off, low & highpass filters designed primarily to uncombine a CATV cable feed to interface to a fiber optics link or for reinserting a block of new programming. Transition from knee to first channel to be rejected is 1.5 MHz. Two brick wall filters can be combined to make an extremely sharp band rejection or bandpass filter.