I was about to answer the 2nd one only, and that the first is not made for the 305. But then I read a review where one person says that he uses it on the 305.

I have the 2nd one (quick release kit). Like the velcro strap better than the original strap when running, then pop it out and put it in the included bike mount when riding. I've been using this for over two years and have never had an instance where the watch "popped out" when cycling or running.

I suppose the first one might provide some extra insurance of not losing the watch since the band is wrapped around the bar, but the 2nd one has worked fine for me.