After its launch in 1920's, Box-Tengor was improved on various structures. The main improvements were as follows:

• Attachment lens was added.
• Shutter locking system was added.
• Focusing screen changed from frost glass to the lens.
• Decoration plate was added around the lens. The earlier type had had the rectangle shape and the later type had the circle shape. Also, apertuer switch lever moved down on this plate.

In addition, we used the earliey model for this feature.