10 x 13 Booklet Envelopes-Brown Kraft 28Lb Big Envelopes-Open Side Envelopes 50 Pack 10x13 10x13 Booklet white Multi-purpose envelopes are ideal for mailing documents, promotional material, catalogs, brochures and much more. These are standard 28 lb. white stock with Moisture activated gummed seal. Open-side style allows easy content insertion and removal Cost-effective,Heavily gummed Check O Matic 100% Satisfaction Guaranteed -Comes 55/per pack