Alvin - Heavy Duty Clear Vinyl Envelope - 30x42 - The Alvin Heavy Duty Clear Vinyl Envelope is .13 mil thick vinyl and its waterproof zip top closure protects valuable documents from dirt, dust, and moisture. Great for commercial or marine applications. Notations can be made on the clear, vinyl covers by using a grease pencil or waterbased felt pen and wipes clean with either a dry cloth or soap and water. These Heavy Duty Clear Vinyl Envelopes are perfect for business, contractors, architects, sports, pilots, surveyors, engineers, builders, navigators, artists, and more. Alvin is one of the primary sources for drafting supplies and drawing equipment in the country. Creative Coldsnow is a pround retailer of Alvin graphic arts, drafting and fine arts products.