Interesting. They need to work on the finishing a little. Self extractors are a pet peeve of mine. Great concept for a problem that did not exist. Crank arm extractors are a great tool and one of the more satisfying ones to use, especially when you feel the crank arm release from the spindle. With self extracting bolts, it asks too much of the hex wrench to loosen a tight bolt. Most of the time they work, but if they don't it can get ugly.