Series 4 fans were first made to resemble General Electric plastic fans with a back-clamping, split hub. Other manufacturers have machined the hub on the back to function as a bearing cover, or used a set screw near the back to mount the fan on a short shaft. We added flat-backed fans with equivalent dimensions for GE motors. The front hub is easier to heat and to tighten the set screws. These flat-backed fans are designated 1-001 through 1-103 in the Series 1 blank bore fans.
Select the Overall Diameter Range (D) that the fan you are looking for fits into.