This is a true MPPT charge controller. The open box and lower price did not impact functionality. I have the readout meter so i can tell how well the controller is working. I'm using it for 360 watt solar panel. it is working as expected. I would buy again if needed.
This is the best controller I can find without breaking the bank. I've used PWM controllers before but and clouds and they shut down this just keeps charging without fail. Spend the extra money and get the best.