22" tall, 6" base, 2 3/4" neck.
the medium seems more in-line with ATB's small... The medium has an 8" base and 3.5" neck. The recommended pump on the i-tech medium is actually a sicce.
So if you want to compare the i-tech with the ATB, as I'm sure you do GSM
It's probably a more fair comparison to choose the i-tech medium to the ATB small.