Our printed DoorJamms are made of synthetic rubber. This printed DoorJamm is clearly marked with "EMS" on both ends on one side. This product is versatile, stretches over 200% its original size, reusable, easy to carry, weather and chemical resistant. The printed DoorJamm will withstand temperatures as hot as 212 Degrees Fahrenheit and as cold as -40 Degrees Fahrenheit. This product weighs approx. 1 ounce, can be stored nearly anywhere on your person or kit, and allows you to carry multiples without being cumbersome.