4 pieces of band in each set. Triangle 3-way direction elastic fastener to secure flat sheet or fitted sheet. Hassle free method to straighten sheets all the time without hard work. Fits various size of mattress from twin to King size. dependable elastic band to withstand harsh stretching and abuse. Metal clip with reinforced fabric protector plastic gripper to hold bed sheet securely without tearing or damaging. Approximately, each band can be adjusted from 5 inches to 13 inches with desired tension strength. Simply place the one clip on center corner of the sheet and use remaining 2 clips to further secure the sheet. Apply same steps on each corners of mattress. NO HEAVY LIFTING!!!