DURABLE PLASTIC. Signs use 55 mil thick HDPE (high density polyethylene) and can last up to 2 years outside. Signs have a 100% recyclable base material. ROUNDED CORNERS. Signs have rounded corners and burr-free corners for safe handling, longer life and a professional appearance. DIGITAL PRINTING. Signs are digitally printed in high resolution and over coated for additional protection. INSTALLATION. Signs have pre-punched and pre-cleared mounting holes for easy installation. Signs mount to walls, fence posts and doors, and can be used indoors or outdoors. PROMOTE SAFETY. Let everyone know about the area's danger with this Explosives, Keep Out sign.