All four were assembled when I put 4 new tires on my 2008 M35 Sport Infinity. I was a bit worried after the tire dealer installed them because they didn't register in my car but needed to be programmed. I took my car to my local dealership and it took 5 minutes to program it with the specialist scanner required. So far, so good! All four accurately display my cars tire pressure information on my dashboard. Very satisfied and saved a lot of money considering each OEM sensor can cost up to $80. Definitely recommended.