The second design in the Explore Wisconsin Series is here! The Keeper design is one that many Wisconsinites can relate to - dropping your line in the cool waters that cover this beautiful state. That's what Wisconsin is all about, especially in the summertime! At 15 oz, these sturdy mugs hold a generous amount of whatever you have in there. (not my business what you put in). They advise you to hand wash to prolong the design and they are microwave safe.