Beautiful bed frame, easy to install.. but when we selected King Size in the drop down menu, we expected the frame to perfectly accommodate our King Size box spring ad mattress.  Ultimately, after placing our box spring and matters on the bed frame, we found there was a gap between the mattressbox spring that measured about 8” .  Wayfair and the manufacture worked well with us through the process of finding a solution.. we were sent a new box of rails and bed posts to see if they rectified the issue.  Unfortunately they did not , but we appreciated their efforts. We will just get inventive and find a way to make everything work.  All and all quality product.   Just review the dimensions of the bed carefully,  perhaps twin and queens have a tighter tolerance.  We have a lull king size mattress .