Yale 2000 and 2100 series Maximum Security Cylinders The range of Maximum Security Cylinders consists of the Yale 2000 Series and 2100 Series. Both offer a flat dimple key and maximum resistance against manipulating, drilling and pulling. The Yale 2100 Series offers additionally a patented key profile so you can order original Yale keys by showing your Yale code card. 2000 SeriesMaximum Security Euro Profile Cylinder with Dimple keys. Drill protected and supplied with Code Card. 2100 SeriesMaximum security PATENTED Euro Profile Cylinder with Dimple keys.