JMI Telescopes makes this medium Universal Wheeley Bar to support and more easily transport larger field tripods and telescope rigs. It comes upgraded with 5" hard polyurethane locking wheels that raise most tripods 6.4" off the ground to provide more clearance while moving your rig to your observation point. The Wheeley Bar has a maximum payload capacity of 100 pounds and tip receptacles with an inside diameter of 2.25" and is adjustable to fit tripods with a tip-to-tip distance from 33 to 43". JMI recommends that this medium Wheeley Bar NOT be used for 12" or larger Schmidt-Cassegrain telescopes (SCTs), even if the mount is listed as being compatible, as these telescopes are too heavy for this size and suggests using the large size instead.