This is a new for fall 2017 Backpack & Lunch bag pair.
It's modern style, with cool CG poses for Sonic, Tails & Knuckles. The material used is all really shiny / glossy, giving both bags a bit of a different look. The background is Green Hill from (probably) , and the backpack has a slogan "Come On Step it Up!"
Unfortunately, the lunchbag is always positioned in front of the backpack in any photo anyone can find of this set, so it's hard to see who's on the pack itself. It does have 2 mesh side pockets, regular back straps & a hang loop. Where is this sold? Possibly Amazon, but likely somewhere else too. It's 16 by 12 inches, and should be around 14.99 if you can find it for sale.