What kind of triangle / ruler is shown in this video? https://youtu.be/p8LBr6cZPuY?t=530

At roughly the timestamp above the architect uses an odd looking metal straightedge and I was wondering what it was called. I thought it was a regular architect's scale at first, but two of the fins are small. I can't make out any brand marks and have so far had no luck finding out what it is. 

Have any of you seen something similar?
It’s a ‘Brown + Sharpe toolmakers knife-edge #530’

In the video he was probably just referring to the second ruler he showed with the bevelled edge.