Sheet Suspenders ® are two (2) individual suspender straps made of the finest woven elastic that adjust to any size. Most importantly, Sheet Suspenders ® are easily slipped under any type/size mattress, EVEN A BABY'S CRIB to form a cris X cross. There is absolutely NO LIFTING OF THE MATTRESS NECESSARY and they NEED BE APPLIED ONLY ONCE! The four easy-open clips have nylon inserts that will not damage sheets. As seen on Good Morning America & Tested, Approved and Recommended by Good Housekeeping Institute for crib sheets. WE ALSO RECOMMEND A SEPARATE SET FOR THE MATTRESS COVER WHICH IS NOT CHANGED AS OFTEN AS THE SHEETS. Perfect for any bed from Boats to RVs and even waterbeds. Sheet Suspenders was invented & patented by Maria Thornhill in 1988, after an accident resulting in spinal cord surgery that left her bedridden close to a year. While in bed she discovered there was no way to keep fitted sheets securely on the mattress, they kept slipping off the corners. With Maria's strict back limitations of "No Lifting or Bending", she invented the perfect solution! Sheet Suspenders ®.Now 20 years later; sheet manufacturers tried to improve this difference with "deep fitted sheets," claiming to fit any mattress. When in fact the larger sheets alone are not the true solution; now we have too much sheet that hangs on the sides, letting us see that Sheet Suspenders are still necessary. Made in the USA. When CHANGING THE SHEETS DO NOT LIFT THE MATTRESS. The weight of the mattress keeps suspender straps in place. Lift four corners of fitted sheet a little, unclip. Put new sheet on and re-clip four corners. FOR ALL Mattresses; Put fitted sheet on. Lift corner of sheet & clip suspender strap to sheet, tuck sheet corner back under. Walk suspender along side of bed, while slipping under the mattress to the opposite front corner, lift corner of sheet & clip, tuck back under. Repeat steps 1 & 2 on opposite corners to form an "X". Slides should face foot of bed for adjustments.