This product is a hot dipped galvanized boat trailer equalizer bar.  It is commonly called the EQ-356.  It measures 6 1/4" from center to center on the two bottom holes and measures 2" tall.  This equalizer bar, or pivot bar ties together the suspension on tandem axle trailers.  It has 9/16" diameter nylon bushings.  It measures 1 3/4" wide.  This equalizer bar is more common on boat trailers than on utility trailers, but has seen a variety uses.  It's galvanized finish will help keep rust from forming.

The 9/16 Inner Diameter bushing that comes pre-installed is suitable for most land trailers. If the purpose of this equalizer bar is for a boat trailer, you will most likely need to replace that bushing with a bushing with a 1/2 inch inner diameter. The appropriate one for this Equalizer bar measures 11/16 Outer Diameter, available here Trailer Leaf Spring Bushing 1/2 inch ID, 11/16 inch OD