OK, that sounds good. We had some problems with horn relays in unconventional applications some time ago, so I thought I'd bring up my experiences in case you were going to try to use one in a constant-on situation. No problem with a momentary-on application like a horn. If you happen to have a really heavy-current situation like charging an auxiliary battery, there's a continuous-duty version of the round solenoid switch available like a Ford starter uses. We use one of them on our motorhome to disconnect the coach batteries from the starting battery system when the engine is not running. This system prevents discharging the starting battery during several days in a campground, running interior lights, etc. off the coach batteries.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!