What happens if you don't have the blue dot facing forward?

Glass ampoules are scored so they break behind the blue dot. Attempting to break the amp in the wrong direction won't work.

Normally, an ampoule put in the amp snapper the wrong way round won't break, so people will realise that something is wrong, and fiddle with it to make it work.

If people try and force it, sometimes the whole ampoule will shatter inside the 'safe snap', but this requires a lot of force, and the broken glass should remain within the snapper.

To prevent this happening we recommend that services have an open box of water amps in the needle exchange, and that they demonstrate correct use of the snapper to everyone the first time they collect one.