Eupako #1 Coin Envelopes 100 PCS are made of high quality US kraft paper, these 2.25″ x 3.5″ brown coin envelopes are recyclable, sturdy and durable. Sturdy Coin Envelopes: Made of high quality US kraft paper, Eupako 2.25″ x 3.5″ brown coin envelopes #1 are sturdy, durable and seals firmly.