This foundation was a complete disappointment. After using inexpensive box springs under our King size Leesa Hybrid for the last few years, we decided to splurge on the foundation. But the beams that run down the middle of it (that take the full weight of the mattress) are completely inadequate. They are hollow- two thin boards along the top and bottom with a few supports along the way, then covered in black fabric so you can’t tell. We couldn’t figure out why we were sagging so terribly at night, then we lifted the mattress off and realized we could flex the center beams down with just the weight of a finger pushing down. So my husband had to remove the two supports, and replace them with solid lumber that he had to cut down to size. If Leesa used solid wood supports instead of the manufactured hollow beams, I would give the foundation 5 stars. But unless you are handy and can replace parts yourself, I do not recommend this foundation. Leesa told us they would reimburse us for the lumber, but that hasn’t happened yet.