Tensile Strength: 4, 100 psi (Poor) Impact Strength: 1. 1 ft. - lbs./in. (Poor) Hardness: Durometer 68D (Medium) For Use Outdoors: Yes. Specifications Met: ASTM D4976, UL 94 HB. Also known as starboard, these sheets and bars won’t degrade when exposed to salt water, humidity, and UV light. They’re more rigid than standard HDPE sheets and