This giant 20 ounce Harry Potter mug features the vow, I Solemnly Swear That I Am Up To No Good, plus an area where you can add a photo of your very own. Just click the Customize It button to create your one-of-a-kind gift that will be cherished forever. This white ceramic mug holds 20 ounces of your favorite hot or cold beverage and is microwave and dishwasher safe.