It is considerably larger than the usual tobacco tin.

From the BCB site:

CN550 Mini Mess Box

A super lightweight, airtight aluminium tin with locking roller clasps. It features a rubber seal within the lid, and is useful as a storage tin for personal survival equipment.

Size: 13 x 9.5 x 3cm (5" x 3.5" x 1")
Weight: 95g (4oz)
(RRP £12.92)

http://www.bcbin.com/store/cat_human_aid.asp?idproduct=96&idCategory=27