The SM-66 is the integration of the high performance GPS patch antenna and a state-of-the-art low noise amplifier into a very low profile/extremely compact/fully waterproof enclosure. When connected to a GPS receiver with +4.5 to +5.5 VDC antenna power, it can provide excellent signal amplification and out of band filtering & rejection for that receiver. Last but not least, the design of a double lock (or an anti-theft locking nut) provides sound security for the product.