If your worried about this thing fitting STOP !! This fitting fits inside the standard 4" collection hose no problem. As for the reduction end it's also true and mated with my shop vac hose just fine. Here's a little helpful hint. If your having problems with fittings or your dust collection hose has a weird tweek in it and won't fit up under your machine like you want. Use a heat gun or a hair drier to slowely heat up the hose and then position it however you need to. Now get out there and collect some dust.