Standing in line at Autozone I decided to see if I could open my FOB without watching a video on how to do it. Pulled out the emergency key and there was the groove to open the fob with the tip of the key. I was surprised how small is the circuit board. The fob is large and bulk compared to the board. Has anyone found a replacement case that is smaller? I'd try just putting the board in my wallet if the thing wasn't so expensive.
I found one that I really enjoy...its not a FOB per say, but its a cover that goes over it....... BTW...what does the key do that is built into the FOB? If you go on AMAZON and search for item B007FUVQCO you will see it
The mechanical key is a backup to your SKS fob. If your battery dies, you can unlock the door manually and hold your SKS fob up to the Start button for several seconds then start the car. SCH-I535
To the OP, there was a thread here about the Lexus card key. It is about the dimensions of a credit card, but not as thin. I'm not sure if anyone has been able to get one reprogrammed and working on the Prius. SCH-I535