Maximize workout intensity! Our heavy duty resistance bands have many applications. Build explosive strength by securing them to barbells, dumbbells, and machines to provide progressive resistance during traditional exercises (squats, bench press, etc). Heavy duty workout bands can also be used for general strength training, assisted pull-ups, assisted dips, powerlifting, stretching, and ballistic training drills. They are super thick and highly resistant to wear and tear. Bands are 4.5 mm thick with the exception of the 4-inch band (XX Heavy), which is 6.4 mm. All bands have a layered design, which minimizes the chance of them breaking at a single connection point. If a band gets nicked, it won't snap easily because multiple layers help to keep it intact. This product may contain dry rubber or natural latex.