I made the mistake of purchasing a series of 7 DVDs of Winkelman's katas. I have seen these katas performed better by yellow and orange belts. These disks are a total waste of money if you are looking for something to really show you proper form. they are fine as a refresher to remind you of the proper order of techniques, but nothing more than that. To see a supposed master walk through a kata rather than display proper form is shameful. Seiuchin kata performed without bent knees, some stance changes pivoted around a stationary leg instead of stepping through, Naihanchi kata walked through with back turned to attacker at times... too many mistakes to even list.my qualification? ni-kyu in Ishin Ryu, many years of doing these katas with a 7th dan who insists on perfection.