The Duncan Butterfly is the yo-yo most people picture when they picture a yo-yo, and the shape is the whole reason. Where a classic imperial yo yo has straight sides that taper toward the string, the butterfly flares outward, which widens the gap the string has to land in. That is the difference between a trick that catches and a trick that clatters off the side, and it is why this is the shape handed to a beginner first.
It ships as an assortment. Beyond that, what you are buying is a yo yo toy that pays back ten minutes of practice with something a child can visibly do, then keeps paying it back for years. For a yoyo for kids, or a yoyo for beginners of any age, that wide catch zone is worth more than any feature anyone could bolt onto it. It also travels well, costs less than a movie ticket, and asks for nothing but a flat ceiling and a little patience.
How do you use a yo-yo? A yo-yo is used by slipping the string loop over your middle finger, winding the string around the axle, and throwing it downward so the remaining spin carries it back up to your hand. Butterfly-shaped yo-yos have a wider flared gap between the two halves than the classic imperial shape, which creates a larger catch zone and makes string tricks easier to land.
