2018 Pop Century Purple Millie Bobby Brown, Gaten, Caleb, Sadie QUAD AUTO /4. This autographed quad card features the signatures of Millie Bobby Brown, Gaten Matarazzo, Caleb McLaughlin, and Sadie Sink from the popular TV series. A rare and prized collectible for fans of the show, this limited edition item is a must-have for any avid collector of television memorabilia. Perfect for display or as a unique gift for a fellow fan, this quad autograph card is a standout piece in any collection.