Also, the Zefal can't be beat as an emergency device for discouraging the occasional dog that is, shall we say, overly-enthusiastic. I would not hesitate to use a Silca for the same purpose if needed, but it is problematic whether the Silca would survive the encounter, while a Zefal will do what it needs to do and come back for more,

The last time I had to use a Zefal for dog discouragement, just having it my hand was enough to make Fido stop in his tracks and slink back home, giving my the stink-eye the whole way. This clearly had not been his first experience with the business end of a full-length bike pump.