I've recently bought a Sunpak 120J TTL bare bulb flash to use with my 135 , 120 and large format cameras .
It's a TTL/ Auto / manual flash with an assortment of shoe adapter modules to work with various brand cameras .
Because it's a bare bulb , with a large reflector, the resulting images are a out the same as with flash bulbs , and an improvement over magic cubes ( though I have those too !)
They give a nicer lighting than regular flash guns .
Sunpak 120J Auto Pro "TTL" Parabolic Reflector Flash Kit with TR-Pak II Battery Pack with Charger, Guide Number 150 at Normal Position ISO 100 ft.
www.adorama.com
I got mine off eBay UK for £120 , I already have several modules that I use with the two ring flashes .