The Metal Reducer 200-125mm stands out for its strength, adaptability, and effortless integration with solid plastic ducting, as well as insulated or uninsulated flexible ducting and fan spigots. Featuring male ends on both sides, this reducer is meticulously engineered to snugly fit inside solid plastic and flexible ducting. To achieve a polished fit, fan spigots and duct fittings may need a small piece of duct.