Review on Ayniff Set of 4 Adjustable Triangle Elastic Bed Sheet Fasteners - Keep Your Sheets Neat and in Place with Heavy Duty Gripper Straps by Tina Jones

Installation instructions - I did this and it wasn't too difficult: Lay the sheet on the bed as usual. Headboard - Corner 1 - use the end of the fastener without adjusting the length in the middle. Fold the corner of the sheet over, fold over the clasp and fasten the two clips. Place the corner of the sheet back on the bed and fold down the clasp to allow the sheet to slide on the corner. Push the bed with the latch in your hand and lift the bed slightly to allow the latch rubber to engage. With the latch in hand, move to the opposite corner at the foot end of the bed and it is now diagonally under the mattress. Fold the corner of the sheet and attach the two clips and place the corner of the sheet back onto the mattress. If necessary, tighten the central length adjuster under the mattress. Now make another corner at the head and then down to the foot in the same way. Hope it works for you :)