I wrote this a few years ago as a simple guide to rebreather diving. Rebreathers aren't complicated but there are a ton of books written about diving that make it sound like alchemy. They're bollocks, generally, and usually more about cementing some high-falutin' instructor's position as a mega-guru. I'm just a punter so published it anonymously. Or I could just be saying that because no-one really knows who wrote it. Who cares? Buy the book.