Inlet Cuff (Swivel version) - for connecting 1 1/2" (36mm) oil resistant hose to any Alto/Wap, Festool or Fein vacuum. Threads onto the hose ribs (reverse thread). External diameter for the part that plugs into the vacuum is 2 9/32" (58mm).
Note - for coupling hoses, you'll need to use one of these couplers at either end of the primary hose and a Coupler Sleeve.