Not that i know the unit myself, so it's not a recommendation.
But apart from a few ringlights that connect to studio flash generators, i know no other ring flash that will fit Hasselblad (and even this unit needs some adapter rings to make Sunpak's adapter ring fit.
The Sunpak does offer TTL OTF control, when used with the Sunpak DX module HA2D, and a Hasselblad camera that offersthe possibilty of TTL OTF control, of course.
> There is a MF ring flash offered by Sunpak for Hasselblad (and > others). I think it is 12RX ( the 8RX is a 35mm version I believe)??? > Hasselblad use to have a ring light for there equipment as well, and > it occasionally shows up at Ebay. Currently there is a twin macro > flash on Ebay (item # 3823002873) that you may want to look at. It > comes with filters, and works directly with the TTL metering of the > TTL capable Hasselblads. I use one on a 553ELX. The nice part is that > you can vary the lighting of the two flash units individually with > diffusers, filters, etc, which adds some depth to macro shots.