I dont know about helping with flexablity but will definatly get some double takes.
Nosightsneeded,
I don't think this collar is necessarily more flexible than the collars she has been using, but having the radio and GPS collar running on top of this 4" collar, will reduce the amount of coverage by 2". That is where I think the dog will pick up some flexibility. Due to the design of her previous cut collar, I was not able to attach a radio collar, nor was I able to run the GPS around it, as it was too bulky. Hopefully this will resolve those issues. If not,then I will try some other ideas out, until I find one that does work.

TrueBlue,
If you decide you want a collar down the road, get me your dimensions and I will make one. We owe you something for all the photography tutorials/ lessons....