If I was stranded on a deserted island, the three objects I would want in my possession are: 

1. Leatherman
2. Duct tape
3. Rubber grip jar opener

Rubber grip jar openers are usually used by old people and weaklings.  But like duct tape, it's easy to find more and more ways to use them.  I just loosened the head on my cordless drill so I could remove the bit.  I couldn't do it in my own strength.  Only with the help of rubber. #products