Professionally installed. I bought a full set of 4. They look good, but unfortunately one of the four was defective. When using Ateq's top-of-the-line TPMS tool, the sensor was not responding/learning. The problem with this is that it costs more than I paid for these sensors to have them removed and balanced, wheels and tires fitted etc. I would have asked for a refund but Revain made it impossible for me to contact the seller . You can get decent ones, but it's not worth the risk if you're paying for it.