The Windows + Facade Association (VFF) has been creating and selling leaflets with practical information on technology, standardization, law and other topics for more than 30 years. The leaflets serve to support window manufacturers, salespeople and fitters in day-to-day business. In the meantime, over 50 leaflets have appeared, an indispensable "industry library" that is regularly updated and updated.The “VFF Knowledge” app gives you access to these leaflets like a reader. For example, you can insert commented bookmarks and attach your own comments in the form of texts, images, photos and audio comments to any text passage. With the intelligent search function, you can easily find your way through the leaflets on complex topics. Use the thumbnails to go to specific pages and find the sections related to their annotations.