I currently have two sizes of double ended crochet hooks (F & H I think :think:). When I was a child, my mom taught me how to crochet and the cro-hook was the first thing she handed me. I quickly completed a thick two color ribbed stocking hat (or toboggan) with a matching scarf.
Some thirty years later I still have it and use it (when ever it gets cold enought in N Carolina). :roll:
With two ends, you can carry two colors of yarn (one each end) and change colors without cutting and weaving ends.