My Dad's a big lab fan; They are sweet dogs, but they're pretty big, aren't they?
Why a size limit?
They aren't much bigger than some Aussies. Males should be 60-80 pounds, females 50-70. AAM's little lab is pretty small. The classic Labrador should be no more than 24 inches at the shoulder. Some of the field lines are bigger, but you can usually get a feel from the parents.