Sqrgreat USB DC 5V to DC 9V Voltage Power Supply Cable - USB to 9V Cable with DC Jack 5.5 x 2.1mm, Tip Negative(-) Design, Max DC-5V-to-9V 0

Was terrific for converting battery powered fan to USB.

Works perfectly with a Samsung USB wall adapter to power a Strymon Cloudburst. It's center-negative so it works with most pedals right out of the box (bag); no polarity conversion required. Doesn't feel flimsy, but I wouldn't go yanking it out by the cable. Might not last as long if installed where its constantly being jostled. There are less expensive adapters that look identical, but most I saw were center-positive, and I was willing to pay ~$4 more to avoid the inconvenience of either using a polarity converter or re-soldering the leads. Make sure your USB power source has enough amps on the 5V side for the 9V power draw (roughly twice what you need on the 9V side).

Disappointing. It didn't work...just got very hot, so I can't use it.

Using these to power various petals through battery pack works like a charm

I use a battery brick to power my overdrive pedal. Works great!