Axle clips fasten wood axle caps to the steel axles and come in every ½” in lengths starting at 2½” up to 7”. This measurement is the portion of the clip that is flat and does not include the threaded ends. Picture “a” is the clip bars that goes under the axle which the axle clips and spring clips “c” are fastened to. These clips are threaded with 5/16” threads and include square nuts. The spring clips “c” are half-round between the threads. I have some pre-bent for 1½” or 1¼” springs and also straight, which can be shaped to any size.