A classic optical square consists of two high-class pentagonal prisms closed in a plastic protective cover.

It ensures quick right angle sighting and horizontal lines determination. A very easy plumb bob mounting. With its high quality cut, the accuracy is more than 1’.

The prism is coated with silver at the bottom and at the top so that sightings at ±45° above or under the user’s level is possible. A big window between the prisms ensures a clear and bright image.