The Viking VK3541 Quick Response Conventional Sprinklers are small, thermosensitive, glass-bulb spray sprinklers available in several different finishes, temperature ratings, and K-factors to meet design requirements. The special Polyester, and Electroless Nickel Polytetrafluoroethylene (ENT), coatings can be used in decorative applications where colors are desired. In addition, these coatings have been investigated for installation in corrosive environments and are listed as indicated in the Approval Chart