With non-factory applied glass coatings there is a direct trade off between longevity and repellent. Water Repellent Coating for Glass and Perspex is designed to offer the maximum possible repellent while offering reasonable durability. Water is blown off car screens at speeds as low as 30mph and on vertical glass water rolls off leaving a virtually spot free surface. Glass that is coated with this will stay cleaner for longer and any contaminants such as bugs and ice will be much easier to remove.