Your fitted sheet is worn out but the flat and pillowcases still new! It's very common that fitted sheet wears out much sooner than flat sheet and that is due to that fact that fitted sheet is subjected to body and feet friction much greater than flat sheet. Our Twin Extra Long Fitted Sheet 340 Thread Count 100% Pure Cotton gives you the option to just replace only what you need.

Dimensions: 

Twin-XL Size: Twin-XL Fitted Sheet 39 inches wide X 80 inches long Fit up to 15 inches mattress deep.