Sentry SR The Sentry SR Series of lasers are the latest in laser technology designed for both level and positioning applications. The Sentry SR operates up to 25 m and is housed in a rugged, explosion-proof enclosure. The Sentry SR Series of Level Monitors/Object Positioners are: - Optimized for short-range applications (less than 25 m) - Available with a cooling plate option, extending operation to 150°C. All Sentry SR Series Level Monitors are available in DV and CP models: - DV: Optimized for performance in environments with excessive dust and vapor - CP: Optimized for clear path applications.