I have 6 of the mustang mv-5600 search and rescue vests. These are impact rated at 100mph (not rated to help you survive the impact) and are very comfortable. They are similar to the mv4600, however the mv4600 is not coast guard approved (only approved by the Canadian Coast Guard) like the mv5600. I bought mine from Amazon.com because everybody else marketed them as in stock (Machovec) and after you buy them send you some BS with several week lead time. You can check my thread "StillCrazy Velocity...Resurrected" for pictures of the jackets.