This fan duct is designed for the GoodWe inverter 10k-et and its + version. It's made for a 92x92mm fan, intended to pull hot air from the inverter's fins and direct it upwards. You have the option to print one or more, but three would be the best fit. It's important to note that the model doesn't cover the right part of the inverter because there aren't any fins there. I recommend using PWM fans along with a board to regulate the fan speed. This model is modified, not made from ground up from me - dimensions changed to fit the inverter but the locking mekanism is from other model, but the original link is not working anymore, if you are the one feel free to send me the link and I update it.