to replace the key must 1) Get the old electronics box: this is not a problem (the card and the battery fit perfectly, and the buttons work fine (former key 308 SW.) 2) Where it is complicated a bit, it is the replacement of the key blade of the rotation system, This eliminates the need to resize the supplied blade. For this, use a pin hunting (or a nail and hammer) to recover the blade of the old key. (The nail diameter to use is to check on the supplied blade.) 3) raise the blade to the new housing, a new pin is provided to mount the new case. a little tricky space to insert the new pin is very narrow and now a new key replaced for a small fee