Pair of leather world war 11 stitched leather dial gun sight cases

Pair of lovely leather cases. I believe they are for dial gun sights. The label inside one seems to say Sight dial N09 MK1. All fastening intact and fitted interiors. F.Ltd O.S.13378. Stitching good. One case has 16550 painted on it. Size approx. 33cm x 19cm. Would look lovely polished up.