The Kreg Heavy Duty Trak KMS7704 is an L-shaped, hard anodized aluminum extrusion with five T-slots which accommodate the head of a 1/4" hex bolt. Measuring 2-5/8" high x 1-3/8" wide, the shape of the track allows enormous flexibility when locating and mounting the track on the different machines in your shop. One face has an indentation sized for a 1/2" wide self-adhesive measuring tape.