These are usually used to help keep a quilt secured on a child’s bed - at the bottom of the bed it clips onto one side of the cover, then an elasticated strap goes under the mattress and then clips onto the other side of the cover.
Please leave a contact phone number - due to an increasing number of time wasters I will no longer respond to any request that does not include a contact number because, apart from a very small minority, the majority of people who do not leave a phone number do not respond to my messages I send through Freegle offering said item, and then I’m left chasing and or waiting. Thank you if you understand.