Review on Eiechip DC to DC Step Up Boost Converter Pack of 10 - MT3608 with Micro USB, DC Voltage Regulator - Boost Module for 2V-24V to 5V-28V 2A Power Supply by Jaleel Pruitt

I bought them about 3 months ago and took the advice to turn the potentiometer clockwise a few times and then using a DMM turn the potentiometer counterclockwise until the correct tension is reached. I've gotten them for a variety of uses, but mainly to step up the voltage to a 120mm 12VDC fan (up from 5VDC) in a custom RPI case I've repurposed from a PC power supply . They work GREAT! Of course, PC fans draw almost no current, so I didn't expect the module to get hot, and it doesn't. I used the module to power 9VDC from 5VDC. The 12V DC was spinning the fan too fast and I didn't need as much airflow. This is of course the simplest application of this module. I haven't tried anything more sophisticated, but it was a cheap and reliable solution to a design problem where a component required more voltage than the project's supply voltage. I will buy more. None of the 10 I received failed at all.