Thermalgard Slotted Caps are intended for use in elevated temperatures. The glass reinforced nylon shell has a beaded edge for improved rigidity. Thermalgard Caps meet all applicable requirements for a Type I (top impact) helmet as outlined in ANSI/ISEA Z89.1-2009 (Class G) and CSA Z94.1-2005 (Class G). These caps also meet the voluntary standard for reverse donning and low temperature [LT] as prescribed by ANSI/ISEA Z89.1-2009. Look for the official reverse donning logo to determine if your hard hat may be worn backwards without voiding approvals.