I think these are the ones made by Dale Pitcher. If they're the ones I'm thinking of, then what I've heard is that they're incredible, but I have no firsthand experience. You can probably find out by calling Dale Pitcher at Intuitive Design (307) 532-2616. As I understand it, they are NOT being sold under the Intuitive Design brand name, and the brand name may be changing. Dale Pitcher is the person to call to find out for sure.
