The first one I got arrived with a VERY wrinkled skin (huge bumps) and also a severe rattling sound as the spring had cut into the skin and wasn't attached tightly enough.
I contacted Thomann for a replacement. The didn't want the first one returned and sent me a replacement immediately. Great customer service.
Unfortunately the second one had more or less the same problem. I didn't bother contacting Thomann again as they had already sent me two and it's such a cheap item that it didn't seem worth the hassle with return shipping, customs documents, etc.
So, instead I tried fixing the problem myself. There were basically two problems:
1) The wrinkled skin that made the drum sound like a cardboard box. I heated the skin with a hair dryer and it tightened up nicely and sounded pretty good. Sadly it didn't last long until it was back to it's useless, wrinkled, cardboard sound. Also, if I heated it just slightly too much it got TOO tight and lost all tone. So basically I have to heat it a very specific time every time I use it and then it will be useable for maybe 1-2 hours.
2) The rattling sound from the spring vibrating against the skin. I fixed this by jamming some glue into the hole where the spring goes through the skin. This fixed the problem on ONE of the drums. The other one was not succesful and it still rattles. Might try it again but I really can't be bother anymore with this right now. Plus the drum looks kinda ugly with a lump of glue on the top...
These are cheap instruments but they should still WORK. The ones I got do not work as advertised. The recording on the Thomann website sounds a LOT better than the ones I got before I (sort of) fixed them. With the glue and careful heating ONE of the two I got sounds pretty good now... until it requires re-heating... which melts the glue... who know how long it will last...