Fair enough, like I say I'm not familiar with the subject but curious. I was more picturing the masks that look a bit like gas masks that have radios in them. M

Fair enough, like I say I'm not familiar with the subject but curious. I was more picturing the masks that look a bit like gas masks that have radios in them. My extent of diving knowledge is limited to movies and Mythbusters, I'll admit. Thanks for that information :)