Specifications include, but are not limited to: Lihue 2 EPA Protocol Standard Mixture, Certified to ±1%, 2000 psig Nitrogen Dioxide 10.0 ppm -- -- Air 660 Aluminum 8" x 48" Lihue 2 EPA Protocol Standard Mixture, Certified to ±1%, 2000 psig Sulfur Dioxide 10.0 ppm -- -- Nitrogen 660 Aluminum 8" x 48" Oahu 2 EPA Protocol Standard Mixture, Certified to ±1%, 2000 psig Nitrogen Dioxide 10.0 ppm -- -- Air 660 Aluminum 8" x 48" Oahu 4 EPA Protocol Standard Mixture, Certified to ±1%, 2000 psig Sulfur Dioxide 10.0 ppm Carbon Monoxide 2500 ppm Nitrogen 660 Aluminum 8" x 48" Oahu 2 EPA Protocol Standard Mixture, Certified to ±1%, 2000 psig Carbon Monoxide 200 ppm Nitrogen 660 Aluminum 8" x 48" Oahu 2 EPA Protocol Standard Mixture, Certified to ±1%, 2000 psig Sulfur Dioxide 5 ppm Nitric Oxide 10 ppm Nitrogen 660 Aluminum 8" x 48"