What is this for?
 

https://cimg8.ibsrv.net/gimg/www.jk-...bf25e77ad6.jpg
Can anyone tell me what these hook like devices are on the rear of the soft top frame? What are they used for?

There is a strap that snaps to the upper part of the frame. When you go to remove the top from the jeep, you want to unsnap that strap, slide it down the pole, and loop it over that hook. If you do not, your spring-assist top will give you an unwelcome surprise.