I have had this mat for over 2 years now. I ordered it off Amazon for maybe $20 at the most but I'm thinking it was a little less. I have a shoulder that is constantly numb due to an old tennis injury that can really drive me crazy if I have been sitting for too long or am not careful to sit with good posture at the computer. Whenever my shoulder is bothering me or I just feel like relaxing this is my go to. At first when you lay on it you will feel a stinging. In my opinion it does not hurt but pain is subjective. After roughly 30 seconds the stinging becomes more of a warm feeling. I highly recommend this if you have any back pain/issues or deal with tight muscles. I can't tell you how many times I have fallen asleep on this thing. Its that relaxing! I also have the neck roll version and it works just as well.