These double flare plugs are made from ceramic withblue caprice glass glaze. They have a wearable area of 5/16″ between flares. Eachplug is hollow to reduce the overall weight and act as a diffuser for essential oils (optional). Just 1-3 drops per hole will last about 1-3 weeks. These are hand made, so please allow slightvariations in the glaze colors and sizetolerance of +/-0.5mm.Choose your size below.