The Shop Vac 2.5" to 1.25" Conversion Unit part # 9068500 allows the use of accessories for a 1.25" hose (opening about the size of a golf ball) with a 2.5" hose (opening about the size of a baseball). Use this conversion unit to use smaller size accessories with a larger hose. Compatible with 1.25” accessories and 2.5” hose for wet or dry pickup.