Each hat comes with a note explaining that the hat is an Official Prefect Hat and is to be worn at all times.
(Despite the adamant note, it turns out no one will care if any of the prefects neglect to wear their hat ... the exception being Elric's hat. The Sorting Hat has enchanted Elric's beautiful tiara to be removable only under special circumstances.)
to Gryffindor prefect Brienne of Tarth: a socialite's multicolored butterfly hat.
to Gryffindor prefect Beowulf: a plastic anachronistic viking hat w/ fake fur.
to Hufflepuff prefect Skwisgaar: a teddy bear hat.
to Hufflepuff prefect A: a pink fuzzy cat hat.
to Ravenclaw prefect Admiral ZEX: a huge red organza bow on a headband.
to Ravenclaw prefect Wishbone: a woodsman's cap.
to Slytherin prefect Damien Thorn: crocheted devil horns.
to Slytherin prefect Michael Scott: a rainbow hat.
to Sparklypoo prefect Elric of Melnibone: a tiara bearing the Sparklypoo house crest.
to Bitchiwitch prefect Chiri Kitsu: the Velvet Crab.
to Bitchiwitch prefect Raptor: a most kawaii kitty hat.