Oatey 15427 Hercules Pro Dope 1 Pint Thread Sealant Screw Cap with Brush Oil-based thread sealant. Not for use on plastic pipe or fittings. Gray color. Non-setting formula; will not harden, crack or become brittle. Accepted for use on FlowGuard Gold pipe and fittings. Oil-based thread sealant Not for use on plastic pipe or fittings Features a gray color Non-setting formula will not harden, crack or become brittle Can be used on lines carrying natural gas, air, steam, hydroid heating, ammonia, brine, diluted acids and sprinkler systems