1. Specifically designed to protect sensitive receiver front ends from high levels of RF effects from nearby transmitted signals; 2. The SDR receiving antenna is very close to the transmitting antenna, or the antenna support or other system failure causes a high RF level to enter the receiving antenna input, which may cause the SDR receiver to freeze;Measured: The receiving antenna is 10 meters away from the transmitting antenna, and the transmitting function is 1000W. The SDR receiver can work normally. 3. Input and output: M female; 4. Only receive the front end protector, 50 or 75 ohm compatible; 5. Protect your preamplifier and radio from excessive RF and lighting. colour: silver Material: plastic size: 25x25x112mm Package Contents: 1*SDR Receiver Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.