![Keystone Tugboat #504](http://www.collectingkeystone.com/wp-content/uploads/2015/06/Keystone-Tugboat-504-150x150.jpg)
![Keystone #504 Tugboat Box](http://www.collectingkeystone.com/wp-content/uploads/2015/06/Keystone-504-Tugboat-Box-150x150.jpg)
This is A Keystone Tugboat model #504. It is 10″ x 3.5″ by 3″ tall. The stack has a K B instead of the more common K. An educated guess is that it stands for Keystone Boat. The box is plain and early in design so I believe that the tug is from the 1930’s.
From my private collection.