[Size] 3/8-18 NPT,can work with 8mm hexagon wrench. [Material] Aluminum alloy 6061-T6, black anodized. [Seal] The allen head 3/8 NPT plug is sealed by a 60 degree tapered thread.(Sealant or PTFE tape is recommended for installation) [Parameter] Working pressure: 1500PSI. Temperature range: -65°F-259°F. [Installation ] Easy to install,just use a hex key to screw in.