This is a used, tested, and refurbished in line duct blower for 4 inch duct. It runs on 115 V 60 Hz AC, and draws 39 W at 0.46 A. The item was used in a laboratory experiment circulating warm air for one solid week, then dismantled and stored on a shelf until now. There is a cosmetic dent in the housing that does not interfere with operation. The pictures.

Both ends have a diameter slightly less than 4 inch, suggesting it fits into 4 inch duct on both ends.

This in-line blower uses a high quality German blower motor EBM model R2S133 – AA 40–21.