I had some Space Bag knockoffs to load up with clothes recently, but the end of the hose on my vacuum cleaner has some notches in it that make getting a good seal a bit of a pain.  This simple adapter blocks those notches.

This might also work with other Dyson vacuum cleaners of similar vintage (mine's about 12 years old).  The outer diameter of the adapter is 35 mm, and it extends 30 mm into the end of the hose before a ring keeps it from going further.