Wizarding World of Harry Potter Remembrall. Clear with on/off red illumination. 100% authentic Universal Studios theme park product. Lights up when you push the button.
Neville Longbottom received one as a gift from his Gran at the beginning of the 1991–1992 school year. As soon as he held the Remembrall in his hand for the first time, it turned red, indicating he had forgotten something. The problem was he could never remember what it was that he had forgotten.
Remembralls were also banned in the O.W.L.s because they would be used to cheat.