Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: What is the polarity of the plug?  Center positive or negative?
Document: I've become addicted to Tripath amps. I got 2 so far and will probably get a few more, but they were being shipped with underrated 2 amp supplies that choke when you crank the amp up. This to me seemed like the fix. I was right! They have more than enough amperage to run the amps, the plug fits perfect and it has the correct polarity (positive tip) for both my Lepai LP-808 and TA2020.
Plug it in and connect to the device to be powered. In my case, it was a telescope. It performs as advertised. It's simple. The product appears durable.
I bought a number of these and they are very handy. The power plug fits 2.1mm x 5.5mm female CCTV adapters and now I can move my power supplies from device to device with ease. I would buy again.
I also got for a LED string set. The 'brick' is small, the DC plug end fit perfectly. Silent, zero buzzing. 12 month warranty, Amazing Amazon Fast Ship and a great price. What else can I ask for?
Worked great for my 16 ft RGB LED strip! It is worth noting that the adapter I received was slightly different than the picture. The wall plug had a ground (three prongs instead of two) which could be an issue for some consumers. Definitely worth the $8.00 I paid.
Plug and play ... I had a Jalapeno Bitcoin Miner that was not running and fast-flashing it's red light. After a couple of searches, I found this might be indicative of a problem with the power supply. Sure enough, I ordered this replacement and plugged it in... Voila! My miner started working again. Thanks!
picture showed a 2 prong plug. I received a 3 prong (grounded) which is better, so thank you. BUT, product ad said it was 6 amp and the one I received was only 5 amp! That is not good! I think it will work just fine, so far it has. But I feel they need to represent what they are selling better. You should get what you see.
As the picture shows, this has a two-prong plug. It does run warm, which is why I spec'd a 6A adapter but am only using 4A. Using this for LED lighting (strips). Has worked well so far, but be aware there is a 3 second delay from plug-in to the time the adapter supplies 12V. I plan to leave this plugged in and install a switch on the 12V side.
Search for Car Shiatsu Massage and see what you find.Wouldn't you know it? I misplaced the AC adapter for home use. The pillow needs a relatively powerful AC adapter, and I had a couple at home that would power the massager under no load, but couldn't keep it running when I leaned on it while sitting in a chair or on the couch.So, I took a chance on getting this 12V Adapter Power Supply, for LCD monitors, with the hope that its plug would fit the massage pillow. Lucky me!
Received product from vendor M.TOP which differed from what was pictured.Pictured is a power supply with a 2 prong plug (ungrounded), however I received a 3 prong plug (grounded).While grounding is likely an upgrade for most users, it did not meet the needs for my specific application.Amazon customer support was good about confirming should be an ungrounded plug, and providing for the return and suggesting alternate vendors, but still a hassle.Power supply appears to work as expected when plugged into a grounded outlet.
Answer: Center Positive.