Important note: We provide 3 sizes, 51/54/58MM. Please measure the inner diameter of your coffee basket before purchasing (for example, if your coffee basket inner diameter is 51mm, you can purchase a 51mm doring ring). Item Name: Dosing Ring Material: Aluminium Alloy 51mm doring ring is suitable for 51mm portaiflter. 54mm doring ring is suitable for 54mm portaiflter. 58mm doring ring is suitable for 58mm portaiflter. 51mm dosing ring size: base inner diameter: 59.4mm, base outer diameter:65mm, Top diameter: 71.5mm, height:20mm. 54mm dosing ring size: base inner diameter: 62.6mm, base outer diameter:66mm, Top diameter: 74.8mm, height:20mm. 58mm dosing ring size: base inner diameter: 70mm, base outer diameter:74.5mm, Top diameter: 78.4mm, height:20mm. Package Included: 1Pcs * Dosing ring. Notice: 1. Please allow 1-3mm error due to manual measurement. pls make sure you don't mind before you bid. 2. the color may have different as the difference display, pls understand. 1. Designed to work with the 51/54/58mm Portafilter baskets. 2. Coffee Dosing Ring stop wasting coffee and messing up your work top. 3. Coffee powder funnel is made of premium aluminium alloy, non-rust nor corrosive, food grade material, safe to your family's health. 4. (51/54/58mm) portafilter funnel is dishwasher safe, you just rinse it with water and clean it with brush or sponge; As for use, you simply place the funnel atop of your portafilter while grinding, distributing and tamping, and removed funnel quickly when finished. 5. (51/54/58mm) Dosage Ring eliminates overflow and spillage improves dosing weights and shot consistency.