Of all the spa mfrs that spec covers, only Arctic does better with materials and workmanship with that Castcore foam. That said, I have a huge problem with their only 1" of fall on their slope as the foam is only 3.5"->2.5".
I think Shaamus must be referring again to the HS cover, with those figures.
The Arctic castcore cover is nominally 5/4 (actual measurement - I went to the factory showroom with a tape measure and checked three different covers- is 5/3-7/8. Yes, there's a 1" slope, but our pitch--if you'll pardon the pun--is that the thicker steel-reinforced cores will not sag and so will not puddle...)