I've got a set of doubles on the work bench, with no idea if they're heavy or light doubles. I've got an email out to Supertech, but before I wait a month for them to respond, does anyone know how to measure a difference between the two? Is it the seat spacer? inner spring coil thickness? spring height? Any insight would be greatly appreciated.

 

All I could find:

 

Ah, I should be able to measure with rate and maybe coil bind, assuming I can accurately measure both. Thanks! I'll post my findings for future reference.