Philips FRx Infant/Child Key
The key can be used over and over again with no need to replace it. Compare that to the cost of replacing pediatric electrode pads on other AEDs and you'll experience the savings. The HeartStart FRx Smart Pads 2 are used for all emergencies.
It seems easy to use and install, however I haven't been able to locate just where it should be placed into the unit.
No experience, to date, thankfully.