These Harvik yellow, size 11 dielectric safety boots are made of SBR blended natural rubber with a polyester lining. They are abrasion/chemical/oil/slip-resistant and meet CSA/ASTM standards. The boots have a withstanding voltage of up to 10kV/37kV in wet/dry conditions, 12-inch height, and 527 Degrees F heat-resistance for 60 seconds.