According to OSHA 29 CFR 1910.212(a)(5), “When the periphery of the blades of a fan is less than seven (7) feet above the floor or working level, the blades shall be guarded. The guard shall have openings no larger than one-half (½) inch.”
The fan guard safety scale is a tool to easily check the openings in a fan guard. The blue-colored scale is made out of durable, 0.090"-thick anodized aluminum, it has a 0.25"-diameter hole, and it has easy-to-read text and graphics that will not rub or scratch off. It is about the size of a credit card, which makes it convenient to carry and store.
Part # FGSS-150