Poly pads stay in place without straps or loops when fitted correctly. With a cotton outer shell and poly filled center they are fully machine washable and quick to dry. They afford excellent back protection and you choose the thickness that you desire. Poly pads are soft and flexible, but tough and long lasting in everyday use. All Purpose 25" X 36" Poly pads come in three thicknesses: Single: 4 cm. of Poly fill Plus One: 6 cm. of Poly fill Double: 8 cm. of Poly fill