The Hard Wire Kit gives your detector seamless integration into your car. If you are a bit handy with automotive electrics then this is the one for you. If you are not confident enough to install the hardwire cable yourself, then you will need a Mechanic or Auto Electrician (for example a car stereo shop) to do it for you.
Order this one if you do have basic electronic installation experience or are going to ask a mechanic or automotive installer to install for you.
Works with both old style Talex and BTST.
(Price includes shipping)