Permanently lubricated upper and lower ball bearing system that ensures long life and no maintenance; all-aluminum rust free construction; exclusive vari-pitch base adjusts to 12/12 roof pitch; tested to withstand winds of 110 MPH. Easy installation and reduces winter ice buildup. Forever guarantee - residential use. BIB12 Dade County Approved 11-0822.05. BIB14 Miami Dade County Approved 10-0928.05. BIB12 features a 20" x 20" base and 17-1/4" height. BIB14 features a 22" x 22" base and 20" height. Turbines are exhaust vents.