I REALLY wanted this to work. I have a recording studio and a lot of knobs and controls that need cleaning without changing the settings. I ordered this first one and it doesn't charge. There is no red light. I tried three different USB outputs and combinations; different cables. Nothing. I'm still desperate for this type of product, I'm a sucker, I even ordered a SECOND one month later. Now this one is on the charger. But it didn't turn on. 3 second delay made. I checked the position of the filter three times. Nothing. Both were sent back, they only returned the money for one. I won't be going a third time, it's lovely.