Duotight 8mm (5/16") to 6.5mm (1/4") Push-In ReducerThe Duotight 8mm to 6. 5mm Reducer is a precision push fit adapter designed for the modern draft system. It allows you to transition seamlessly from 8mm (5 16") OD tubing to 6. 5mm (1 4") OD tubing without the need for clamps or tools. Featuring the patented double O ring system, it provides a superior gas tight and liquid tight seal, even under high pressure. This fitting is essential for balancing lines or connecting specialty beverage equipment.