This axle is designed to work with our 35mm narrow glide trees or any 35mm trees that are around 5.5in on center. This Axle is machined from stainless steel so rust is not an issue. This axle is 3/4 (.75in) diameter. The way this axle is designed you can easily turn it down to 5/8 (.625in) or any size in between. K model /early sportster hubs are 17mm (.669in) so you can turn it down to that size as well.