they believe their factories are controlled environments and this allows them to use smaller driers.
i just found this info out the other day.
the first 2 numbers on the drier is the size of the drier and the last number is connection size.
163s = 16cu in and 3/8 sweat
164s = 16cu in 1/2" sweat
165s = 16cu in 5/8 sweat
607s = 60cu in 7/8 sweat
and so forth. never really paid attention until an ol' timer told me