These spindle-to-track adapters are a must if you have a Doorway dolly. They provide an affordable solution to get you on a track. Don't have a Doorway dolly? Some of our customers prefer these to the 360 Swivel wheel assemblies citing that the ability to mount these on a spindle or axel give them more freedom to design their dolly. They are 6" long and mounted on 1/2" aluminium bar stock, allowing them to easily support upwards of 1000 lbs. Each wheel assembly rotates 360 degree's as well as the steel spindle mount tubing. As with all of our products these are precision machined to a tolerance of .004" and come with a money back guarantee. Have a question? Click here