Alumicolor Select-a-Scale are an ultra convenient and functional drafting tool that allows architects and engineers to select multiple scales all in one product.
The unique design incorporates a sculptured arch on the bottom for ease of movement. A rotating rod on the top displays one of six available scales while the solid aluminum base has fixed scales on the front as well as a raised inking edge.

Fixed Scale: 50 parts per inch

Rotating Scale: 10, 20, 40, 10:1, 20:1, 40:1