In this system, one player pressures the ball at all times. The name of the defense reflects the behavior of the other four defenders—they attempt to "pack" within an imaginary "line" located about 2 feet (0.6 m) inside the three-point line, with the main goal of stopping dribble penetration, only venturing outside the line if their assigned player is preparing to receive a pass. When the elder Bennett first developed the system, he actually taped a "pack line" to Green Bay's practice court as a teaching tool, and when he moved to Wisconsin had a similar line painted on the team's practice court. The system has become increasingly popular in 21st-century college basketball. Among the other prominent coaches using the system include Chris Mack (Xavier, now Louisville) and Sean Miller (Arizona). Variations of the system have been used by Ben Jacobson at Northern Iowa and Brad Stevens when he coached at Butler.