I have a Photek Softlighter 54" Umbrella & Diffuser with a 7mm Shaft that I have used only once! If you have studio lights and are looking for something great to diffuse the light this is great, I just bought a softbox as well, and prefer it.
Here is a link to the exact one I have...
http://www.adorama.com/PTSL547.html?...hter&item_no=4
I paid $80 totaly after shipping, I'm asking $60

If you have any questions, feel free to PM me or email me! (jeremynshell@highstream.net)
Thanks!!