Hi Andrew. This is a unit-specific replacement part, so the manufacturer does not provide specs as the replacement part should be selected for the specific unit you have to ensure compatibility. Please reach back out and provide the Brand name, Model and Serial numbers off of the unit this part goes into and we will be happy to confirm the appropriate replacement. You can also contact us via any of the options listed here: https://www.supplyhouse.com/sh/control/contactUs We offer phone call, email, text, and live chat!
Hi Andrew. This fan uses a 3/8" bore size.