Natural Latex Mattress Thickness: SOFT/MEDIUM: 9" has a 2" comfort layer; 10" has a 3" comfort layer, 12" has a 5" comfort layer and the cover is 1. The 10" & 12" have a softer feel, if you’re a side sleeper or prefer a softer mattress. The 9" is ideal for side sleepers who need a little more support. MEDIUM-FIRM/EXTRA-FIRM: Firmer latex is used in the comfort layer on 9", 10", 12". Body weight is the deciding factor here. 9" is best for up to 225 lbs; 10" up to 275 lbs; 12" up to or over 275 lbs.