Premium Tyvek Sleeves with Window & Flap. Sleeve size approx. 5" x 5" plastic window is 4" in diameter. Tyvek cd envelopes have a higher strength-to-weight ratio than paper and other cd sleeve materials. It's not only significantly lighter than paper it's stronger. Which can be pretty important when you're sending discs by mail. Tyvek cd sleeves are incredibly water and moisture-resistant making it just as protective in a hurricane as it is from a coffee spill at the office. Liquids simply run off its smooth surface keeping the contents perfectly dry.Weight is lighter than white paper sleeves but the material is stronger than white paper sleeves.Reduced shipping costs while protection is stronger than standard white paper sleeves.Automated packaging grade quality.Good for both end user customers and large volume replication factories.