I am guessing he means the Indexable wrenches, not "Flex Wrench"?
EDIT: Looks like GearWrench calls "Indexable" and "Flex-Head" a "Flex wrench"
for anyone who owns these, where have you found these to be particularly useful where other wrenches lack?
I bought them on Monday, already used them on Wednesday (and I am a DIY-er) for a bolt that my hands weren't strong enough to turn, that a ratchet wouldn't fit on, and that my pathetically short CM RPs were too short to reach. Sure, a normal long wrench would have been fine - but the "piston action" (I think that is the "official title" for it) made removing the bolt ridiciulously faster. (Toyota 1MZFE in a '94 Camry. Damn I hate those cars now. Go Volvo)
These are great for FWD transverse-mounted engine work.
Another note: They are super long - AWESOME