Commercial Electric 81765 Installation guide

Hello! I have reviewed the instructions for the Hampton Bay Crossbar Kit model 488 208. This document provides guidance on its installation and specifications, including its adjustable range, load rating, and compatibility with different ceiling box sizes. I'm ready to answer your questions about this product.
What is the load rating of this crossbar kit?

What sizes of ceiling boxes is this crossbar kit compatible with?

What is the adjustable range of the crossbar?