This is a pair of Trailer Leaf Springs rated to 2500lb Capacity Total, or 1,250lb capacity each. Leaf springs should always be replaced all at once, and many trailer in this weight capacity use 2 springs so we offer a pair of springs to make replacing them easier. The Slipper Style Leaf Springs will require a bolt of either 9/16 inch or 1/2 inch diameter (the pre-installed bushings are 9/16 inch ID) to install to your trailer, and the slipper end fits into your trailers Rear Spring Hanger. The hardware is not included with this set of springs.