What Is It? game 272

W00t! It's time for another collaboration with the ever-excellent What Is It? Blog. Can you guess what this odd item is used for?

Place your guess in the comment section. One guess per comment, though you can enter as many guesses as you'd like. Please do not post any web link or URL - doing so will void your entry. You have until the answer is revealed on the What Is It? Blog tomorrow.

Two prizes: the first correct guess and the funniest yet wrong one will win a T-Shirt from the NeatoShop.

IMPORTANT: Please write your prize selection alongside your guess, so visit the NeatoShop and take a look around. If you don't write your prize selection, then you don't get the prize. I think you'll like the selection of funny t-shirts and science t-shirts -or even t-shirts of your favorite blogs and websites.

See another picture of this object at the What Is It? Blog. Good luck!

Update: this is a traveler, or tire measuring wheel, according to the Dictionary of American Hand Tools it was used to measure the length of flat strap required for making a new wagon tire, further explaned at the What Is It? blog. The first correct answer came from Berhard, who wins a t-shirt from the NeatoShop! The funniest answer came from Rodney McDonald, who said it is "a moral compass with a handy grip!" That's good enough for a t-shirt, too! Congratulations, and thanks to everyone who played this week.