In response to popular demand, we have made this very nicely cast brass horn for 16mm, (or similar scale) models. The horn itself comes with a well hollowed out trumpet and can be cut down to any length so that various length horns can be made. The horn base has an M4 thread and is supplied with a nut and washer. Once the horn has been cut to the desired length, it can be soldered or glued into the base. 
The 'normal' maximum length overall is about 28mm, but longer horns can be made if some of the 'waste' sprue is used. So creating a two or even three tone roof mounted horn is now possible with this very nice 'one size fits all' Swift Sixteen brass horn casting.