The Master Lock snap-on lockout hasp with tag has a spring-loaded locking arm that pushes open then snaps closed and can be kept from reopening by up to five padlocks (sold separately) as part of a lockout-tagout (LO/TO) safety procedure required at facilities where a device or energy source needs multiple-person authorization to be accessed safely. Its spark-resistant, anodized aluminum body and stainless steel parts are durable and corrosion resistant. The hasp ships with three (English, French, and Spanish) high-visibility warning labels with erasable areas for task-specific details. This hasp measures 7 x 2-7/8 inches (17.8 x 7.3 cm), and its closed jaw forms an oval measuring 1-3/4 inches (4.4 cm) short inside diameter, 2-1/8 inches (5.4 cm) long inside diameter, with a 1/2" opening. The five padlock holes in the hasp accommodate shackle diameters up to 9/32". When used according to manufacturer's recommendations, this product is covered by a limited lifetime warranty against defects in workmanship or materials.

Lockout-tagout (LO/TO) safety procedures, as defined by Occupational Safety and Health Administration (OSHA), require that lockout devices be durable and standardized. Lockout devices use color, warning labels or tags, and a physical barrier to temporarily prohibit machine operation or power activation, and reduce accidents, during maintenance or repair. Lockout hasps are often used to secure energy sources in the off position during maintenance or repair when multiple workers are on the job. They consist of one shackle (or clasp) that can be locked closed by one or more padlocks, providing the ability to use multiple padlocks in a place where only one shackle will fit.

Master Lock manufactures padlocks, combination locks, and related security products. The company, founded in 1921, is headquartered in Milwaukee, WI.