Cased 

Olympus OM-System Zuiko Macro 20mm f3.5 Lens

No. 200882 (Version 2 - see below)

Versions:-

1.  ZUIKO MACRO f=20mm 1:3.5  (single coated) (Nos. 200xxx)
2.  ZUIKO MACRO 1:3.5 f=20mm  (single coated) (Nos.200xxx -201xxx)

For use with adapter/tube/bellows etc.