When selecting an FSK (Frequency Shift Keying) receiver module, you must prioritize frequency stability and sensitivity. Ensure the module operates within legal ISM bands (e.g., 315MHz, 433MHz, or 868/915MHz) relevant to your target market. Look for a high sensitivity rating (typically -105dBm or better) to ensure reliable long-distance reception. Additionally, verify the data rate (kbps) compatibility with your transmitter to prevent packet loss, and check the operating voltage range to ensure it aligns with your existing PCB power supply.