Promising review: “We have a rather deep mattress and added a memory foam topper. Our fitted sheet would hold some of the time, but we frequently had a corner or two slip off during the night. It was disrupting sleep, so I was ready to safety pin the fitted sheet corners in place. However, no need for safety pins.
"After giving Bed Band a try,our fitted sheet–slipping problem is solved! The clamp design grips like iron, but the best part is the adjustable bands that allow for a quick final fit after installing the clamps. With Bed Band, you clamp each band into place without tension, then you use the quick adjuster to apply tension as needed. This makes for a much simpler installation, and with a product that by its nature needs to removed and reinstalled repeatedly (sheet washing), ease of installation is critical. Bed Bands is the clear design winner here for both function and ease of installation. A stellar product design at an affordable price!” —Huancayo
Get it from Amazon for $12.99+ (available in four pack sizes and three colors).