Perfectmaze 100 Piece Premium #3 White Poly Mailers Envelopes Bags 9'' X 12'' (PM-3) Poly mailer bags are durable for multiple items such as clothing, accessories, office and party supplies, etc. Poly mailer bags contain a self-stick strip for easy ceiling. Peel and Stick Adhesive. Poly mailer shipping bags are very little weight with a dimension of 9'' by 12'' Poly mailer bags are unaffected by water, dirt and tears. Poly mailer shipping bags to ship party supplies, office supplies, and other miscellaneous items.