Background Reading:  4-R: The Shell 

Tips:

-Keep in mind that acrylic/fiberglass is best, plastic/rotomold tubs are far inferior, but foam or inflatables are terrible.
-Ask the salesperson what company makes the acrylic sheet (Microban Antimicrobial is best)
-Check under the cut line along the bottom of the sill to see how thick the acrylic is
-With your fingers under the sill cut, pull up hard to see how strong the shell is (does it flex at all or is it totally stiff?)
-Try to find a speckled shell and check the tightest concave corners near the bottom of the shell to see how many dots per square inch there are compared to the sill area.  If the dots/speckles are visibly bigger and more stretched out in the deeper pockets, it’s an indication that the acrylic is thinned out in those areas – not a good sign.
-If colour doesn’t matter too much to you, go with the “sterling” (white marble) or “sierra” (grey speckled granite).  Those seem to wear the best.
-We recommend you avoid the pearlescent and metallic colours – they seem to be more vulnerable to chemical and UV attack and are more prone to fading and crazing down the road.