4in1 Filter four-in-one filter: All the best-selling receiver radios sdr malachite can be used together, and the good products are worth buying. This product contains four groups of independent band-pass filters, which are divided into four frequency bands. P1 filter is 0.5-1.5MHz, which is suitable for medium-wave radio listening, P2 filter is 4.5-12MHz, which is suitable for short-wave low-frequency band and 40-meter amateur band, P3 filter is 12-30MHz, which is suitable for short-wave high-frequency band, and 20-meter, 15-meter and 10-meter amateur band, and P4 filter is FM. Four-in-one filter can be used with one-in-four active distributor, which can provide pre-filter function for SDR, radio and receiver. Malachite, pre-filter, makes up for the design of malachite radio with all-metal aluminum shell without pre-filter, and reduces the interference of medium-wave and short-wave FM broadcasting and other frequency bands. The filters are divided into four groups: 0.5-1.5MHz, 4.5-12MHz, 12-30MHz and 80-110MHz, which can be used with a 1: 4 distributor to realize multi-channel and multi-band simultaneous reception. (Due to different factory batches, if there is a slight difference in the actual color, it will not affect the use) Color: Black Material: Metal + Aluminum Package Contents: 1 * Passive Filter