SENSIT Multi Gas Monitors are direct reading instruments designed to detect and alert users of hazardous gases in their working environment. We offer portable, hand-held and wearable gas monitors, confined space entry probes and calibration accessories.

About Confined Spaces Confined spaces - such as manholes, crawl spaces, and tanks – are not designed for continuous occupancy and are difficult to exit in the event of an emergency. People working in confined spaces face life-threatening hazards including toxic substances, electrocutions, explosions, and asphyxiation.

https://www.osha.gov/
OSHA Fact Sheet - Procedures for Atmospheric Testing in Confined Spaces - PDF
OSHA Website ResourcesSafety and Health Regulations for Construction
A confined space is a space whose configuration and/or contents may present special dangers not found in normal work areas. Confined spaces may be poorly ventilated and, as a result, contain insufficient oxygen or hazardous levels of toxic gases. Read OSHA Protecting Construction Workers in Confined Spaces: Small Entity Compliance Guide