All of the axles listed here are machined from 4130 cold rolled steel rod. Typically all drilled holes are for a 3/16″ diameter bolt or pin. Threaded axles are 5/8″ fine thread. The 5/8″ nut or washer is NOT part of the axle and should be ordered seperatly Length of thread is 3/4″ from end of axle. Axles with key slots will accept a 3/16″ key. Keys are provided with “keyed” axles. Usually the key is used with hydraulic brake systems. The description of the axle is the ‘Diameter (5/8″) X the overall length. Custom length axles can be supplied. WHEEL PANTS… If your application is using wheel pants then you will require the outboard end of the axle to have a 5/16″ threaded hole in the end of the rod (like a threaded gun barrel). This allows mounting of the wheel pant.