Find the vehicle, then choose a key style

A plain cut key with no chip or battery, common on older vehicles; it works the doors, ignition and trunk by shape alone

• No plastic head beyond the grip, or a plain black head with no buttons
• No battery inside and nothing to program

A cut key with a small chip in the plastic head that the immobilizer reads before the engine will start; it looks like a normal key and can still be cut, but it has to be programmed

• Plastic head, usually thicker than an old mechanical key
• Often no buttons, or buttons for lock/unlock only, and the car starts with a turn

The key and the remote are one piece: the blade folds or flicks out of a head that carries lock, unlock and trunk buttons, plus the transponder chip

• Buttons built into the key head
• The blade folds out or retracts

A separate remote that locks and unlocks the car, used alongside a normal key; older vehicles often pair a fob with a plain or chip key

• A remote that is not attached to a key blade
• You still turn a separate key in the ignition

A fob that does not need to leave your pocket to unlock or start the car; it transmits to the vehicle, and it must be programmed to the immobilizer before it works at all

• Buttons on the fob but no metal blade, or a blade hidden inside it
• The doors unlock when you touch the handle, with the fob in a bag or pocket

The vehicle starts from a dash button while the fob is inside the cabin; the fob needs to be present, powered and programmed, and a dead fob battery can stop the car starting

• A START/STOP button on the dash instead of a key slot
• The fob may slide out an emergency blade for the door

The small metal key hidden inside a smart fob, used to open the door when the fob battery is dead; it opens the door, not the ignition

• A release tab or slide catch on the fob
• A thin blade key stored inside the fob body