Tyvek Himber Envelopes (2 pk.) | Alan WongTyvek Himber Envelopes are great utility poker card size, double sided himber envelopes, brown color, made in very durable tyvek material. They are made for switching and multiple outs: Switch any freely chosen card into your force card Use any two force cards and reveal either one as your prediction Use two double face cards in one envelope to have four possible outcomes Use any blank card with any words, symbols and numbers for the above