Features: Specially designing to protect sensitive receiver front-end from highly level RF effects from nearby transmitted signal. The SDR receiving antenna is very close to the transmitting antenna, the antenna support other system failures cause highly RF level to enter the receiving antenna input, which can cause the SDR receiver to crash. Actual measurement: The receiving antenna is 10meter away from the transmitting antenna, the transmitting function is 1000W, and the SDR receiver can work normally. Input and output: M female head. Only receive front-end protectors, compatibility with 50Ω / 75Ω. Protect your preamplifier and radio from excessive radio frequency. Specifications: Material: Metal Size: about 25x25x112mm/0.98x0.98x4.41inch Package Includes: 1x SDR Receiver Protector note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.