Don't believe the score on Amazon! These guys are the worst.
We bought a cover from them. We even paid extra to get the heavy duty version. It failed in less than a year! The interior plastic sheeting wrapping the styrofoam was so degraded, that little bits started appearing in the tub water. The foam is now so waterlogged, the cover is so heavy, we can hardly lift it.
We live on the central coast of California, so the weather isn't that extreme. We kept the chemicals in balance, and used the tub often enough (generally 3-4 times a week). Our previous cover, the one that came with the tub, lasted 6 years before it started failing, showing we don't abuse anything.
We called the company, and worked through their warranty process. Pictures, purchase documents, etc. The 3-4 day response time stretched to 3 weeks. In the end, they claimed chemical damage, and refused any of their warranty policy claims.
We were offered a small discount on a new cover, they would not honor the warranty for the failed cover made in Mexico.
When I first wrote my review on Google, their ratings were terrible. Somehow they have changed that though. Do your homework, check other review and BBB as well. We wish we had.