3KEY USB Dimmer Switch Cable with 5V 2A Inline Controller, 8-Level Brightness Adjustment for LED Strip Lights, USB Desk Lamp, Re

Pretty cool. It seems to work by pwm or pulse width modulation. There isn't a voltage drop and i think i measured 2000 hz so the duration - going from memory so don't hold me to that - of the power will be reduced as you dim it. It works on most led loads that i have tried it on except a string of flashing leds which go from color to color and also flash in different patterns. This might be because of the chips and programs associated on the chips themselves. On that particular string, they only go to red, probably because they reset on every cycle. No biggie. I like the little dimmer switch. On off and up and down. I recommend it for it's expected use.

My current led lamp has a similar control grip box that failed after a power outlet surge. This usb unit works really well and was easy to install as a replacement led switch & dimmer.0

Used with a USB fan in a van, allows you to adjust the speed. Perfect.

This is an excellent brightness controller, adjustable in 0-9 steps! i recommend buying it, but please note: 5v input, 2a maximum output current.