I don't have verified information on a product named "Metromilan 3in1." To ensure the description is accurate and safe for your live website, please provide the product's active ingredients and strengths, the formulation (tablet, capsule, topical, device, etc.), intended use or indication, typical dosage and route of administration, major warnings or contraindications, and the country/market where it is sold. Once you provide those details I will write a detailed description and a short how-to-use in simple paragraph text.