http://us.lexusownersclub.com/forums/index...topic=9131&st=0
In the above post Blake has mentioned that it is either BR or CR 1216. Yesterday, I purchased Energizer CR1216 and it fits perfectly. And, like I mentioned in the above link that it works 10-15 feet away from the car.
Taking the top cover out is a little hassle. There is only one screw that holds it together. A little below the loop [part that where the key chain goes] thats where the top part and the bottom part are attached together [like lock&key]. You just have to use a little more pressure to get it out. There is NO way you are going to damage the interior of the key.
Below is a picture key without the cover, as you can see everything is protected so you can not damage anything. Except, there are some metal pieces in the hole, where the battery fits in to, this is the only part that you have to be carefull with. As you can see, this is my second key and when I bought it did not have the top cover; thats why it does not have the small metal pieces that hold the battery in place.
The key looks a lot older and dirtier than what it realy is. It seems that way because the pictures is zoomed in alot. Plus, it has been without the front cover for, I guess a long time [crazy last owners].
Overall, just you a little more power. It is not going to break, if you are carefull with it.