Lexus GS300 1998 Owner's Manual page 24

11L003
Since a transponder chip is not built in this flat key, you
cannot start the engine with this key. Use this key to
release the lock in case you accidentally lock your keys
inside the vehicle or trunk.
Insert your flat key in its key case as shown. We recommend
that you always carry this with you for emergency use. Do not
leave it in your vehicle.
NOTICE
D Do not let the key case become bent as the key may fall
out or become bent also.
D The flat key is designed for emergency use only.
KEYS AND DOORS
11