Movement relies on the interaction of joints and muscles. When the range of motion for a joint is limited or the length of a muscle is less than it should be, imbalances develop and body mechanics suffer. Sometimes these joint range of motion or muscle length issues develop as a result of some other disease process (neurological, rheumatic, etc..) or acute injury; sometimes they develop from postural demands of work, sports or activities of everyday living (computer use, extended sitting or standing).
Over time, especially as the body ages, these imbalances can lead to pain, spine issues and joint damage. Stretching is one way to help optimize that range of motion in joints and the length of muscle fibers- and thus combat the risk of muscle imbalances and associated injury.
Some people are surprised to learn that there are actually several different ways to stretch depending on goals, age and other factors. Many are familiar with the concept of static stretching- when you move to the end range and hold the stretch until it seems like it releases. A newer way of stretching is known as Contract-Relax. With this method, you contract the muscle first against a source of resistance, either a partner or strap, before you relax it into the stretch. Contract-Relax technique is a more effective and safe way to stretch tight muscles.
One of the stretching tools I use in the clinic and often recommend to patients is the Stretch Out Strap (SOS), which is especially useful for Contract-Relax stretching. The 72" strap is made of a very durable, woven material that includes multiple loops to facilitate deep, gradual stretching of major muscle groups with greater safety, control and effectiveness than is possible unaided. It comes with a stretching exercise booklet that features photos and how-to illustrations for more than 30 stretches.
Of course, a towel or belt can be used as an alternative for Contract-Relax stretching but these are generally less conducive to full range of motion (and thus sort of defeats the whole idea). In addition, the SOS strap has loops all along its length so it "fits" each individual, no matter how near or far the body part being stretched may be from reach. This makes for more effective stretching and is also easier on the hands.
The book that accompanies the strap is 100% straightforward. The photos are well done, helping to highlight the muscle being targeted for a particular stretch and how to place the strap appropriately. Considering most books on stretching will be about the same price as both the SOS strap and book, it's still a pretty good deal.
Last time I looked, the SOS strap had over 400 reviews on Amazon.com with an average rating of 4.5 stars (Out of 5). That's a pretty good testament to the value of this product. It is available on Amazon as well as a number of smaller retail online websites.