The small one can be used to open lids in jar cans.
Like most of the others that have submitted their reviews, my experience was very disappointing with these strap wrenches. I tried using both of these to remove an oil filter that was mounted vertically which required using the wrenches "upside down." Because the straps are designed to slide down into a channel instead of through an enclosed slot, it was very difficult keeping the straps in the handle when using inverted. Further, the anchor for the strap on the small wrench drops into its anchor point instead of being entirely encased like on the large wrench, so it almost immediately popped out when pressure was applied while inverted. And, finally, the rubber/elastic nature of the straps cause them to slip out of position unless constant pressure is applied.