This is a Double-Eye 3 Leaf boat Trailer Leaf Spring measuring 27 inches eye to eye with a 1,000 lb per spring rating. This black painted double eye style leaf-spring can generally be seen used with 2,000 pound capacity trailer axles with either 4 lug or 5 lug hubs. They can be used either in a single axle or tandem axle setup, and will work great with boat trailers, jet ski trailers, utility trailers, enclosed trailers, and many others. The Spring itself does not come with Hardware, but we do have mounting hardware and spring shackles available as an add-on above. This spring can work with both round axle and square axle setups, the only real difference would be the mounting hardware needed to secure the spring and axle together; if you have a Square Trailer Axle, you will need Square Mounting U Bolts, but if you have a Round Trailer Axle you would need a Round U Bolt Kit. The spring will come with pre-installed 9/16" bushings, however, 1/2" bushings are also available separately if that is the size your trailer requires (we frequently see 1/2 inch bolts used more commonly on boat trailers, while 9/16 inch bolts are seen more on utility trailers and cargo trailers). Give your trailer suspension an overhaul with these 27 inch double eye leaf springs and keep your trailer riding smoothly!