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 criss 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, QVC & 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 adjustable beds. Sheet Suspenders were invented & patented in 1988. Since then we have been the leader in sales all over the world. Made in the USA. Easy use instructions: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.