The Henry G. Dietz Co. Inc. in Long Island City, N.Y., is offering the Model 171D8WC-S ultra-low-differential air pressure switch that covers an operat-ing range of 09.05- to 8-inches water column in one switch. This switch can operate in harsh environments. Its housing is sealed and waterproof, dustproof, oil tight, and acid resistant. The unit meets the shock guidelines of MIL-90D, and vibration guidelines of MIL-STD-167-1, Type 1. Its temperature limitations are -30 degrees Fahrenheit for dry air or gas to 180(F. for more information contact the Dietz Co. online at www.lowpressure.com.