Build-On Brick Mug - BPA-free 12oz Coffee Mug, Garden, Lawn, Maintenance (Grey) BPA-free plastic, 12oz Coffee Mug Mug with exterior building surface compatible with most bricks Washing: Hand wash Compatibility: LEGO, PixelBlocks, Mega Bloks, KRE-O, K'NEX Bricks Grey mug with exterior building surface compatible with most building bricks. Hand wash only.