The revit virgo wb windcollar is packed with featuresprotection featuresouter shellnylon ripstop this is a lightweight nylon fabric woven in a special pattern known as ripstop during weaving thick reinforcement threads are interwoven at regular intervals in a crosshatch pattern in the fabric this greatly increases the fabrics resistance to tearing and ripping making ripstop nylon extremely durablerevit windbarrier fleece the revit windbarrier membrane is laminated between tw