This is a perfect fan for an apartment/condo window to maximise airflow.
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This model is being sold on Amazon for $29: https://www.amazon.com/Comfort-CZ319WT-Reversible-Auto-Locking-Expanders/dp/B0118ECP7M
It has two 9" fans that can blow air out, or pull air in, as desired.
Minimum Width: 22 1/4"
Maximum Width: 32"