Pantera Variable Diameter Drifter or VDD® is the first and only in the world variable and adjustable diameter drifter. The VDD® allows the operator to select any drift diameter as desired by adjusting a counter nut.

The VDD can be adjusted to work with 2 different diameters in one descent, by slight jarring down the first diameter chosen at the restriction found the arms will automatically set to the second diameter previously chosen to continue operations.
This method allows in one descent to the wellbore to calibrate 2 diameters of tubing without pulling out of the hole.

VDD has 6 arms for a better coverage of the internal wall circumference.