In North America, 2006 Cadillac SRX SUVs used a 4-button keyfob with FCC ID L2C0005T on the back. Prior to 2006, SRX vehicles used a similar 3-button remote. This vehicle had seat memory as standard equipment, so the original keyfobs had fob numbers 1 and 2 on the back. These numbers are purely cosmetic; they are there to help the user distinguish one from the other but they have no effect on functionality.
See Cadillac SRX 4-button remote with FCC ID L2C0005T at this link.