What is freight class 500 description?

Answer 1

Freight classes are based on four things: density, freight stowability, ease of handling, and liability.

A truckload of Styrofoam coolers is the "typical" Class 500 load: a 53-foot truckload of them only weighs 650 pounds (I have hauled these), they're hard to handle because they're fragile, they're relatively expensive for their weight, and their breakability means you're probably going to have a damage claim. So the shipper gets charged an arm and a leg.

At the other end of the scale is a 40,000-pound iron ingot. They're very easy to handle, impossible to damage even if you rolled the truck, easy to drive with and very inexpensive per pound. These would be freight class 50.