Sonic Boom Dog Tags!
This is a cardboard dispenser full of Sonic Boom theme dog-tag style necklaces. Each metal tag has a picture of a character (CG) on it. These are blind-bagged, meaning you won't know which one you'll get until you spend the 2.99 to get it. They're meant to be traded with friends, but it makes them difficult to collect instead. You can see the sample there in its plastic capsule. This is at Target stores in 2015 at the front among the trading card/collectible area. 

Look at the close-up photo, it's showing they have a slightly reflective foil backing the art. The back of each tag has the logo, a few characters & number of the tag ex "14 of 24"

At left, you can get a better view of the foil bag packaging & see more example tags. Each tag comes with a sticker card (top left) & the leaflet (right bottom) The stickers are just screen caps of character close-ups from the show without anything added. The tag images are also likely show screen caps. Look at the leaflet, it says "Collect all 24" & then shows you the art from all of them. 24 different things blindbagged will make the full set VERY difficult to get.

Hot Topic also sells these, but they pull them from the cardboard dispenser and mark them up to 5.00+ per tag. They have to do away with the dispenser because it has the real suggested 2.99 price on there. Avoid buying these at Hot Topic, marking things up over manufactuerer's suggested price isn't right.

Discovered by Dustin Lee Autry

This is the complete collection of all of the stickers/cards that come with the Boom dog tags in their blindbags. As you can see, each card-back is in black/white & is also numbered so it's easy to tell which ones you still have to get. Who appears the least? Sticks, with only 2 images. The most is Sonic with 4, while everyone else has 3. 

Photo by Crystal Sonic Fan

Photo by ManicKatie2