1. It is specially designed to protect the front end of the sensitive receiver from the high level RF influence of the transmitted signal from nearby; 2. The SDR receiving antenna is very close to the transmitting antenna, or the antenna support or other system faults lead to the high RF level entering the receiving antenna input, which will cause the SDR receiver to crash;Actual measurement: the distance between the receiving antenna and the transmitting antenna is 10m, the transmitting function is 1000W, and the SDR receiver can work normally. 3. Input and output: m female head; 4. Receive front-end protector only, 50 or 75 ohm compatible; 5. Protect your preamplifier and radio from excessive RF and anti-thunder Colour:As Shown Material:Aluminum Alloy Size: 25 x 25 x 112mm Weight: 82G Due to different batches, there may be differences in product appearance and printed text, which will not affect use Package Contents: 1 * SDR Receiver Protector Only the above package content, other products are not included. Note: Light reflection 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.