Units of measure to use in product and shipping by product dimensions OR add new lengths, for example, if you sell your products using meters yards.
The class set to 1.00000 is your base length (dimensions) class. Any other length classes in there need to be a factor of your base class. So when you add dimensions in any units to your product it will be re-calculated
Default length classes cannot be edited or removed from the system. You can add your own classes specific to your country or business