Air quality measurement apparatus, namely, particle counters; Alarms for the detection of inflammable gases; Carbon dioxide detectors; Carbon monoxide detectors; Digital weather station instruments; Gas testing instruments; Radiation gauges used for measuring the physical properties of materials; Radon detectors; Smoke alarm tester in the nature of a cool burning smoke generator; Smoke detectors; Thermometers, not for medical purposes; Water testing instrumentation for monitoring and detectin...