The Build-On Brick Mug is a coffee mug with the ability to attach building blocks to the outer surface of the mug. The Lego mug is compatible with Legos, PixelBlocks, Mega Bloks, KRE-O, and Knex Bricks. Now you can build something completely offensive sticking off of your coffee mug and make your co-workers look at it everyday as you go to get new coffee. The Lego Mug does not come with and pieces to attach, you must povide your own building blocks.