Radius of your die for the bender?

Just wandering what size die Radius I should get 4.5" or 6"
Ordering this bender

http://www.tubetek.net/index.php
TIAeace:

I'm welding up a bender and was also wondering what everybody finds as the most useful bend radius. I am going to be fabing an exo for the XJ this winter. I'm thinking of going with the tighter radius.

My die I've been using for my whole cage is a Pro-Tools die for 1.75" tube with a 6" radius (240 degree).

jgxj, you might want to look at those a little more, if you are planning on the 4.5" radius, that site lists a max of 1.5" OD tubing.