HD rotor & LD rotor measurments

[Lowl!f3]

Where are these measurements taken to find out which rotors your looking at?
Is this talking about thickness or edge of the rotor? The bearing opening?

3) Rotors: There are two different widths of rotors available on the 73-87 model trucks.
3.1) HD or Heavy Duty rotors: (1-1/4" wide version) available from 73-87
* These will require matching HD bearings and calipers.
3.2) LD or Light Duty rotors: (1" wide version) available from 81-87.
* These will require matching LD bearings and calipers.