It loses one star because the valve (the spiral hose that connects to the mattress) is of poor quality and if you press it a couple of times, it breaks or punctures. Especially the plastic part at the connection. And if that gets punctured, it becomes useless afterwards. It means you need to invest in a heavy-duty accessory where the plastic is durable. Other than that, it inflated 3 kayak chambers and a double mattress in a relatively short period of time. With such a price, it is top-notch. (It also has a deflation function). I do recommend it, but not with this spiral.