Add to Cart SENTRY Environmental Testing Distance Meter ST820 Sentry MSRP: Now: $89.62 Was: The laser aiming rangefinder ST820 series from Sentry measures distances up to 50 ft (15 m) and is fully functional to help users easily perform distance measurement. Thanks to the supersonic technology, all you have to do is... MSRP: Now: $89.62 Was: Add to Cart