One-touch easy installation on sheet metal.Folding flap can close the opening when not in use.Can be used for thickness from 1/32" to 5/64" (0.8 to 2.0 mm).Compliant with flame retardancy standard UL94 V-0.Flap cover can snap open and lock in position.WARNING: This product can expose you to acrylonitrile, butadiene, styrene, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65WARNINGs.ca.gov.