Apparently the Dolosse works a lot better for high energy wave environments like coastline of SA etc. They are used here, and I am sure they considered Tetrapods and there was a reason they weren't suitable.
replyITT the consensus is they don't actually work better, but, were royalty free.
replyNo idea about either, myself.
Another thing is that you need a lot fewer of them to stack to get the same effect. So cost saving.
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