I just bought a "planer gauge on the 'Bay'. It is a Lufkin #900. They are a machinist's tool ,not exactly sure what or how they were intended to be used. I plan to use it for setting projection of corrugated knives on my shaper when they project from the head . ( 3'' knife used in a 2'' head). I think it will also be very handy for setup in a planer ,or changing jointer knives. there are several locations with holes tapped where I plan to attach a dial indicator. Think real cheap rotocator or Oneway multigage. Anyways this is a idea for now ,when I get it we shall see. One machinist site said he uses it for a great doorstop, it is basically two opposing triangles that slide on each other and remain parallel on the top and bottom surfaces.