Review on 🔌 DROK USB Cable DC 5V Boost to 9V 12V Step Up Voltage Converter 1A, USB to 9v/12v Step-up Volt Transformer Power Regulator Line with LED Display by Ronald Duguay

These USB voltage converters work very well. I've only had them a few days, but I've used them for a few hours and they've been putting out 9.1 volts continuously. I use them with a 22,000mAh USB rechargeable battery to power my guitar pedalboard (13 analog pedals, 2 USB voltage converters and 1 USB rechargeable battery with 4 USB outputs). So far, so good! This eliminated the noise I got from my AC connected pedals (I used 2 power supplies which should have been isolated but I could still hear the noise and it was driving me nuts). Great product so far and I think the price is just right, not cheap but not expensive either. I highly recommend it!