Three reasons to buy one of these: 1. Improves the shape of the jet of water from your tap (if it’s an old tap that is. If it’s modern-ish this won’t be a problem). 2. Allows you to sluice out your sink. (If you have a mixer tap you won’t need it either) 3. Because your Nan had one. (Doesn’t matter what kind of tap you have if your Nan had one it must be right.) They measure 6cm long by about 3cm wide and fit most old taps.