The life expectancy and functionality of windows and doors can be considerably extended and improved with just a little maintenance. It is worth it to put a drop of oil once a year on striker plates and latches of the interlocking system. When lubricating window and door mechanisms inside residential buildings it is advisable not to use spray oilers or oilers with large nozzles because of the risk of leaving stains, smells and contamination on surrounding surfaces and close-by objects. The Precision Oiler Pen protects wallpapers, handles and carpets from such contamination.