The Vtronic W150-01 inline axial blower fan is a 2 speed fan with the following specs
(323 CFM high speed and 259 CFM low speed):
NOTE: Some newer models may not be dual speed
You may see people upgrading to another inline fan but few change out this fan. It is already quiet and does a great job. The benefit of an inline fan on the 35, 51, and 63 is more evident.
This fan ships with the Nova 24 and Mini 60.
Details about the Nova 35 and up fan can be found here:
To learn more about exhausting your laser see below: