The Tall Racks are best used with a Z dependent boot either along the X Axis, or with proper spacing along the Y axis, or even a combination of both. The high profile of the Racks make these an impractical use with Z - Independent boots since the clearance needed would need to be so high. If intending to use a Z Independent boot, the tall rack may not be the the rack you want to use, perhaps the short, flush or QCW.