5pack 9v Battery Clip with 2.1mm X 5.5mm Male DC Plug for Arduino by Corpco

I was using this with an AC/DC adapter to power a parallax basic stamp microprocessor instead of a 9 volt battery. It's meant to clip onto a battery and supply the barrel connector end, not the other way around. So you'll have to clip the wires and swap them if you're using it in the manner I am. Works good though

GOOD QUALITY

They work as advertised and well worth the money.

Good for electronics projects and testing. I have used several of these to make different testers for when I don't have access to a power supply and they've held up well so far.

Update: I am editing my review and hence the "title" of the review in order to avoid confusion and misinforming anyone else. Someone posted a comment to my original negative review and their comments was absolutely correct. In order not to confuse anyone I am leaving my original review below along with the video (for your perusal) and will add to the review for clarification: I purchased these for use with an AC adapter to "replace" a 9V battery. I am therefore using this "as the battery" as opposed to what it was designed to be, a "receptacle" for a battery. For my particular application the terminals were reversed but when used as they were designed, the items are wired perfectly fine. My apologies! With that background you are now adequately prepared to read my original (but incorrect) review: I caught this by happenstance. The items are not defective in that they are all connected, the problem is that they are all wired incorrectly! The positive and negative terminals are miswired. If you purchase these check polarity to make sure that the negative terminal is actually wired to the outside and the positive is going to the center. You've been warned! See the attached video...

All 5 of the battery connectors work fine for my arduino. They are hard to get on and off of the battery because they are new. I’m afraid I might damage them. They use the soft plastic case around the part that goes onto the battery, and maybe a hard plastic case might be stronger. Now I can upload one code to my arduino and take it anywhere I go easier.

I read the reviews on polarity issues and I almost hit return before they even showed up. That said, It came before I even got a chance and I tested every one of them on my ARDUINO board and it lit up without any problems. Whew!

Searched "guitar pedal battery connector" and got this. Definitely my fault for not knowing what I was supposed to be looking for.