Gerikt'n Margin Marker from Norway. 
 
 
The Margin marker is an adjustable marking corner square. It can be set from 0 to 25mm with even margins along two edges at 90°.
 
It can be used to mark along straight edges and internal corners. It is ideally suited to marking architraves but it's also perfect any number of marking up applications.
 
The margins can be quickly set using the clearly visible  scale to quickly and consistently replicate different measurements.
 
The Margin Marker also fits easily into a pocket or tool pouch.