"BPF-4" is a bandpass filter for 4 bands (1.8, 3.5, 7 and 14 MHz). This unit can be used in most transceivers and receivers. If need other bands - it is easy to re-build - just need to change the winding and replace the capacitor. BPF is very small and easy for assembly. Dimensions of board are 55x58mm. For adjustment recommends to use NWT or RF voltmeter; or S-meter on air if have no such devices. The Kit consists of all necessary components, elements, wire and manual in English.