At the bottom of the forum page is a list of supporting vendors. You should be able to find what your looking for there. I purchased my set here https://bigboyshobbies.net/catalogsearch/result/?q=gray+ghost
I use amphibian II and find I'm able to hear the tones well, but I've only had my head just under the surface of the water while lake bottom hunting. I cant speak to actually hearing the tones while snorkeling. I'm pleased with my set.