What is the difference between the K19AT-36 and the K19AT-36H

The MAMAC Systems TE-702-B-10-B is a high-precision duct temperature sensor engineered for demanding building automation systems (BAS) and mechanical equipment room applications

and Day & Night furnaces requiring 1/8" ID pressure hoses

the integrated ignition control module will terminate the gas valve circuit to prevent hazardous fuel buildup

Johnson Controls T-4000-3140 Plastic Cover What is the difference betweenProfessional grade Johnson Controls T 4000 3140 plastic covers are engineered for high performance pneumatic room thermostat applications. This horizontal mount faceplate is compatible with nearly all T 4000 series instruments, excluding the T 4100 and T 4600 models. Constructed from durable, white thermoplastic, the T 4000 3140 features a built in Fahrenheit Celsius thermometer to provide clear ambient temperature feedback for facility maintenance