I purchased the 800 Thread Count Deep Pocket luxury Sheet Set because I was having the worst time finding a fitted sheet for our 18" deep mattress that wouldn't come off at night when my husband and I tossed and turned. Immediately upon opening the package, I could tell the craftsmanship and depth of the corner pockets was unique.  I've since washed them 3 times and they have maintained their sizing and even gotten better with time (softer and more comfortable).  Our sleep has improved too!  I will be buying a second set soon to keep as a backup.  You won't go wrong with this purchase!!!!!