The Metal Reducer 200-100mm is known for its durability, versatility, and straightforward installation with solid plastic ducting, as well as insulated or uninsulated flexible ducting and fan spigots. Featuring male ends on both sides, this reducer is carefully crafted to fit securely inside solid plastic and flexible ducting. For a seamless fit, fan spigots and duct fittings may necessitate a small piece of duct.