Welcome to our forum.
I'll going to get the Covermate III when I get the tub. It has gas pistons on each side and it was really easy to "lift" the cover off the spa in the showroom. It also has a locking mechanism on the side to keep it from falling on you if there's windy conditions.It too is black powder coated aluminum but it does hang from the cover's hinge.
It looked like the HS lifter was designed to be installed on the side of the cover - do all covers have this ability or is this unique to HS or maybe all Watkins tubs?
Chas,The same lifters are offered and recommended by watkins for use on their Caldera Spas. They are a nice lift, however we currently don't sell them. We sell the cover mates with our Caldera Spas, and the EZ-Lifter with all of the other brands we carry.