"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 16-0510.26. BIB14 Miami Dade County Approved 15-0831.08. 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."