Bosch HDC250 SDS-Max Hammer Dust Collection Attachment Dual air chambers provide for both dust collection during use and provide suction to the wall Dust port fits Bosch 1-3/8-Inch vacuum nozzle and can convert to 1-1/4-Inch / 2-Inch hose nozzles Replaceable brush ring provides seal for multiple bit diameters Rubber seal maintains suction to wall Optimized for drilling diameters from 1-1/2-Inches to 5-Inches but can accommodate up to 6-Inches if the brush ring is removed