The 41246 sizes from typical home shop vacuum 2.25" up to 4" outer diameter fit. The 2.25" dimension is designed to fit the most common home shop vacuum with approximately a 2.25" inner diameter opening as well as common blast gates and some power tool work stations of a similar size. Combined with the 61666 connector the 41246 can connect to the working end of many hose shop vacuum hoses permitting extension from a 4" diameter hose.