Windhorse Fitness Resistance Band Set-Five Heavy Duty Exercise Bands with Nylon Safety Sleeves-Anti Snap-Anti Wear-Anti-Injury-Great for CrossFit-P90X Workouts-Men-Women-Upper Body-Legs--Dipped Multi-Layered Latex-Iron Clips-Welded Steel O Rings Only Resistance Band Set that Protects 3 Ways. The resistance band is encased with a nylon safety sleeve that benefits you three ways. First, it prevents over stretching of the bands thereby discouraging the bands from tearing. Second, the safety sleeve protects the bands from getting nicks, cuts and slices. Some exercises call for you to stand on the bands, and if you have a piece of glass or stone imbedded in your shoes sole it can cause the band to get one of these which will cause the band to unravel and tear. Third, if by chance the band does snap you are protected from the recoil because the band will recoil inside the nylon safety sleeve. To sum up, prevents over-stretching of bands, protects your bands from damaging effects from standing on them and protects you from recoil if the band should snap. Multiple "Fast Clip" System-You Control the Resistance. Use One or All Bands. You have the ability to change the resistance quickly with any exercise, resulting in a smooth transition during and between exercises. Resistance bands actually work differently than free weights. The majority of the resistance with free weights is at the beginning of the exercise. With resistance bands it's just the opposite. The most resistance is at the peak of the exercise. Think of doing a curl with free weights. The start is the most resistance, but doing the same exercise with resistance bands the peak or end of the curl has the most resistance. So your muscles do get a different workout using resistance bands. This is a heavy duty set. The rings on the handles are welded stainless steel. The handles themselves are heavy duty, you'll feel the difference when you hold them. All the clips at the ends of the resistance bands are made of iron, and the bands are made from 100% Malaysian latex which is the best on the planet. Plus the bands are "continuous dipped' meaning they are dipped, allowed to dry, then dipped again causing multiple layers of latex to form. This method is superior to the "extruded" method which is just a one layered tube of latex. The heavy duty nylon safety sleeve is the ultimate protection for the user and the bands, extending the life of the product considerably. Super Portable & Light Enough to Take With You-Travel Bag Included