How many times have you found that the force of the stitches on your needle have popped the guard off the end, or they simply fall off from the friction of being carried in a bag? Cocoknits wanted a soft flexible something that would actually slide onto the needle and keep the stitches from sliding off. So they had cylinders made of durable EVA foam, in a variety of sizes with an opening in the middle, that accommodates everything from size 0 (or the cord of an interchangeable needle set) to a US 15.