K&E N4092-3 ---- 1925-1937 Scale Set
The "N" designation on 4092-3s is shown in the catalogs after 1925. No actual rules have been seen with the N prefix on them. Several boxes for 4092-3s have be found with the N4092-3 designation. The use of the N prefix was not consistent between 1900 and 1940. Later it was clearly used to designate a change in design to the basic rule. The removal of the N prefix was also used to indicate a change in design. These changes were usually changes to the scale set.
This rule is an example of the box being marked with the N prefix and the rule was not marked.