I use to have a really good one. It was black and pretty sure it was made by Johny Sewart calls. Unfortunately I lost it last year one day out of coyote calling. Have not been able to find the same one again yet. Primos makes a two pack, both are red in colour. I like the smaller one better but still not nearly as good as the black one I had.
The widest selection of diaphragm calls for coyotes is from MFK calls in the USA. Query MFK Game Calls and you'll find them. I've used them for quite a few years and they're excellent.