The king cool standard flat sheet I ordered which also came with the fitted cool bottom sheet, fit my 13" thick hybrid mattress perfectly. The sheets are crisp and and cool to sleep on, which I like. Seams and elastic are well sewn. A few more color selections would be good and being able to select queen size pillow cases for a king set would be a nice option. Thank you for a good product. I am very likely to order these sheets again.