This shirt appeared a bit out of season in most areas, cropping up in the spring of 2007, although it is a long-sleeve. This comes in reasonable (teen-adult) sizes. As you can see, the Sonic is somewhat shiny and decal-like, a near staple of Top Heavy. The background is a detailed fire/flames (why?) with red-washed images of Knuckles, Shadow and Tails. For some reason, Tails is looking quite guilty of something.
A new (and possibly welcomed) theme they are trying is to have a "Kiddy Version" of the adult sized Sonic clothing. This usually has a very similar (if not identical) version of the design on a similar color/style of shirt. As you can see between these two, it is working. This means that no one is left out on any cool Sonic stuff they may want.