Roadwired Advanced Protection System Laptop Sleeve for 13" Notebooks, Compact - Black Exclusive, multi-level protection system includes: Water-repellant outer shell with full zipper closure and weather flap, to protect against the elements. Foam interlining on all sides, to protect against bumps and jolts. Patented Corrosion Intercept lining (originally developed by Lucent Technologies Bell Labs to protect missile and space components) protects against environmental gasses, pollution and humidity, improving the performance (clock accuracy, key response, etc.) of electronics, reducing errors, and extending useful life.