Dust collector universal heavy duty dust muzzle for 7-9" grinders the main difference between the many brands of grinders is the diameter of the bearing housing. This is where all dust collectors are attached. On 7"-9" grinders, the bearing housings can vary in diameter from 1.75" to over 3". On the 4"-5" grinders, the bearing housings will vary from 1.5" to over 2". The dust muzzle ultra heavy duty has solved this problem. The adjustable fingers of the collar compensates for virtually all the differences in these bearing housings. The dust muzzle ultra heavy duty is excellent for grinding fiberglass, concrete, wood, paints and epoxies. It can be used with sandpaper, diamond cup wheels, 8" soft pads and wet-or-dry polishing pads. features: fits virtually all 7"-9" electric & pneumatic grinders convertible flip-up up skirt for grinding close to walls made from 1/4" thick flexible thermoplastic installs in minutes up to 99% efficient excellent for wet-or dry grinding and polishing