This aluminium container was dropped from an aircraft, and used to pass-on messages to ground troops.
The upper half of the tube contained the signalling smoke charge, with a one second delay fuze.

Documents were fitted in the lower half of the container, closing it with an aluminium cap.
The container was to be thrown overboard from and altitude of max. 100meters, after pulling the fuze that initiates the signalling charge. This charge emits yellow smoke for 180-seconds.

Total length : 404mm
Length w/o fuze :
Diameter : 60mm
Weight :
Fuze delay : 1second (Red fuze)

Photos from unknown source.
Information thanks to W. Jordan , Spotter and Krilan.
Good link to photos : www.cockpitinstrumente.de