Dos-jks

I have an '11 2 door that has a plastic stiffener in the sail panel and recently bought an '11 top for my '10 unlimited and noticed it has no stiffener in it. Was there a design change that happened mid year? Is it a 2 vs. 4 door difference? I also noticed the unlimited top felt like a thinner material and wasn't as tight of fit. It ripples slightly in the wind when the Jeep is sitting and not running whereas the 2 door does not. I read an old thread from '08 with the same thing about the stiffener with no real answer and wonder why it's still going on now.