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"Doc spa offers these covers. I'm interested in how well they work."They work quite well, but have a few draw backs. Besides weight, they don't have a skirt to protect the outer edge of the spa."Can they be used with a conventional lifter?"Yes, to an extent. There's only 1 lifter that works with them and it's a "modified" Cover Valet."How heavy are they to open?"Heavy. I think they average 60 or so pounds"Do they scratch up? does the Al start to look weathered soon?"They're much less prone to scuff damage than the typical vinyl cover. I've seen one 15 years old and they still look very good"What are the costs compared to a conventail cover?"About 3 times the cost"How long are they rated to last? (typical life span of the cover?)"There's no rating, but as I said, I've seen them 15 years old and still looking good. Though, the manufacturer only offers a 3 year warranty.