If you have split firmness on your mattress you should only do month 2 and 4.
转动周期 - 第1个月
Flip while keeping the zipper tab at the head end.
转动周期 - 第2个月
Rotate so that the zipper tab is at the foot of the bed.
转动周期 - 第3个月
Flip while keeping zipper tab at the foot of the bed.
转动周期 - 第4个月
Rotate so zipper tab is at the head end of the bed.