Because it comes vacuumed packed, after opening and laying on bed my wife said “it’s to small but as per the instructions it takes 24 hrs to expand.  And it did , nicely. The comfort you’ll feel is firm but so nice.  You won’t sink because the quality is high.  As you roll over the pad does not leave dents of your last position that you notice.  It’s heavy enough to stay in place and I sleep so well.  My king size bed was ok but this pad is like having a new high end, top dollar mattress.  Free shipping and fast. 
It’s been a week and this man is happy.