From Leica Wiki (English)
- Production era - 1940-1955
- Type - Collapsible hood for Summitar f= 5 cm 1:2 which serves as lens cap when folded (per Forum discussion  below).
- Variants - Clamp-on with set-screw and clip-on (as shown) versions
- Reference - Page 108 of Dennis Laney's Leica 1984 Accessory Guide courtesy of Mike Butkus.
- Forum discussion