A Facebook friend asked me what type of hot tub cover he should buy. I told him that he should buy a cover from the manufacturer who follows the ASTM F 1346-91 specification for making hot tub covers. Manufactures use safety devices or material to inhibit the access of kids into hot tubs.
Beyondnice.com is a maker of hot tub covers that follow this specification in its production. It uses high quality vinyl, straps, skirts and vapor barrier in its products.