Vest worked exactly as described. Took it out on a bigger than average day and used the air both at full capacity and half capacity. Duck diving at half was obviously a little easier, and I tested taking a breath underneath and it worked great. Took me a second the first time, but had plenty of time to find the tube and breathe. I would use it on a smaller day or in the pool first before trying it cold turkey, but it doesn't take much to figure it out.
