Features: 4 in 1 Filter All best-sellers receiver radios on the market can be pair with Malachite. This item includes four independent bandpass filters, which are divides into four frequency bands. The P1filter is 0.5-1.5MHz, suitable for mediumwave radio listen, the P2 filter is 4.5-12MHz, suitable for shortwaves low frequency bands and 40 meter amateur frequency bands, the P3filter is 12-30MHz, suitable for shortwaves high frequency bands, as well as 20 meter, 15 meter, and 10 meter amateur frequency bands, and the P4filter is forFM broadcasting frequency, 88-108MHz. The 4 in 1 filter can be used with one to four source splitter, providing pre filter function for SDR, radio, and receiver. Malachite, pre filter, compensates for the lack of pre filter design in all metal aluminum shells Malachite radios, reducing interference in medium and shortwaves frequency modulation broadcasting and other frequency bands. The filter is divides into four groups: 0.5-1.5MHz, 4.5-12MHz, 12-30MHz, 80-110MHz, and can be used with a 1-to-4 splitter to achieve multi-channel and multi bands simultaneous reception. Specifications: Material: metal Size: approx 1.9x4.5x4.9cm/0.75x1.77x0.93inch Package Includes: 1x4 in 1 Filter note: Please allow 1 to 3cm error due to manual measurement, please make sure you do not mind before you bid, Due to the difference between different monitors, the picture may not reflect the actual color of the item.