Leica Slip-On Cap for M-Series Lenses 14002 protect the lens from unintentional fingerprints and the rain. These Leica Caps fit Leica 28-35-50 mm and 16-18-21 mm f4.0 M-Lenses. The individual Leica M lenses are supplied with various functionally designed lens hoods. On several lenses, they are built in, and have a telescopic design. Lens hoods should always be used because they provide the lens with effective protection against stray light and irradiation.