10" diameter. The inline enclosed external rotor fan is a permanently sealed self lubricating ball bearing type which will provide years of maintenance free service. With UL and CSA equivalent safety ratings, this exhaust fan is made for continuous duty; the permanent split capacitor type motor also has an automatic reset thermal overload protection feature. Needed for proper booth exhaust function. 1187 CFM, 0.25" static pressure, the inline Exhaust Fan for the Laguna Pro-X Bench Top Spray Booth is appropriate for venting to an exterior space.