I have never had dealings with this particular method, but from their information they have documented a 100% survival ratio with 784 survival incidents from over 150,000 trained children. Makes sense to provide the tools just in case.
I know when my grandson was just an infant and we had a pool, we had both a total enclosure non-climbable fence, and a water motion sensor, and he was never out of our sight. He could also swim like a fish since he was two years old... but there is always the chance. I am a belt and suspenders kind of guy when it comes to safety, especially kids safety.

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Jim Luttrall
Mr. Inspector.net, Inc.
Allen, Texas 75002