This design is for the butterfly lover! It is a strap that you wear on the back of your head to hook the straps of your face mask on, thus relieving the pressure of the elastic from your ears. It also gives you an easy way to adjust the tension of the face mask with it's multiple hooks. There are 3 lengths available. Small is about 3.5" wide with 1 set of hooks. Medium is about 4.5" wide with 2 sets of hooks. Large (shown) is about 6.5" wide with 4 sets of hooks. The medium and large can be trimmed down if desired for a better fit. These are printed on our 3D printer and have a texture and minor flaws from that process. They are fairly flexible and can be heated (but not too hot!) with a hair dryer and bent for a custom fit. FREE SHIPPING!