Comes with O-ring, leak-proof.Made of brass material, strong and durable, corrosion-resistant, and rust-proof.The depth of the hole is 7.2mm.Effectively prevent slippage and wrench damage.Product descriptionName: First stage Scuba Diving Port PlugMaterial: brassColor: SilverLow pressure plug:Diameter: 12mm/0.47 inch; Height: 9mm/0.35 inch; Screw Thread: 8mm/0.3 inchHigh pressure plug:Diameter: 13.5mm/0.5 inch; Height: 9mm/0.35 inch; Screw Thread: 10mm/0.4 inchPackage Contents:1 piece high pressure plug1 piece low pressure plugOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.