This Kit is used to attach the leaf springs to the trailer axle. 

This hot dipped galvanized kit is for tandem (double axle trailer) axle trailers with axles that are 2 inch x 3 inch.

This kit contains:

4x galvanized 5-hole plates

8x 1/2" diameter 2 1/16" wide  x 5 13/16" long galvanized u-bolts 

16x 1/2" galvanized nuts 

16x 1/2" galvanized lock washers