Buyers must prioritize frequency band coverage (2G, 3G, 4G, 5G, and Wi-Fi) to ensure the device matches the local telecommunications infrastructure. Key metrics include output power (measured in Watts), which determines the effective radius, and cooling efficiency (built-in fans or high-grade aluminum heat sinks) to prevent thermal shutdown during 24/7 operation. For precision, look for units with adjustable power knobs for each channel to control the isolation range without interfering with external zones.