The units i ordered previously were for a factory installed, keyless entry system, Muzica. It is critical that you order the correct key fob after further research. I learned that my tundra, that i purchased used had a dealer installed keyless entry system. There is only one specific replacement fob from this seller that works on my tundra’s toyota dealer installed system make certain that your original key fob has a small red light at the top above the lock button. This replacement fob does not have the red light, but it is the right one. You do not need your original key fob to set up this replacement. So if you lost your original, you can still pair this replacement to your vehicle. The replacement key fob i received was in a small, sealed plastic bag on the outside of the bag. The website to visit for the instructions for pairing the new fog with your specific vehicle is listed on the website. There are two different sets of instructions for my 2006 tundra. I followed the first set of instructions and successfully paired the new fob on the second attempt. The only reason the first attempt failed was because one of my doors was not completely latched shut. Before i started the pairing steps total time to pair with my truck, including the first failed attempt, was about five minutes.