I find these sorts of tags particularly useful for labeling kegs.  Kind of looking at a keg of aging Barley Wine or what not and thinking… what’s in that keg, only goes so far.  Having a label really helps.  You could also use these for buckets, carboys, tubing or anything you can fit the string around that you don’t want to put a more permanent label on.

7/10 1 PM Central: These are selling for just $2.28 (one time purchase price). Shipping is also free to many US addresses with Prime Membership [Try Prime for Free] or a qualifying order. Prices and availability can change quickly.  Check product page for current info – More About Prices

Avery White Strung Marking Tags, 1.75 x 1.09 Inches, Pack of 100 (6732) – note that multiple variations of this product may be available, as such a different version may appear at this link

If you want to get a little fancier GrogTag has a line of keg and carboy labels that are designed to stay on your keg or carboy.  These provide an area where you can use dry erase markers on wipe off markers to label kegs and carboys and notate some additional information.