The 4 to 2-1/2 Cone Reducer by POWERTEC This limited adapter was designed to provide you with a simple solution to coupling your 4-inch ID dust hoses with 2-1/2 ID dust hoses. Specifically, it allows you to step down from a larger main line to a smaller branch line without compromising air velocity or the effectiveness of your dust collection system. It features a premium, heavy-walled ABS plastic construction made for durability and to withstand the wear & tear commonly associated with woodworking dust collection. It&rsquo’s extremely easy to use and does not require messy tape or additional equipment. POWERTEC is a leading manufacturer of high-quality woodworking tools and accessories, machines, and an assortment of OEM replacement parts.