Features: This loss prevention tracker is compatible with Apple's "Find My" app (Apple devices only) and can locate lost items. Shape: It's a thin card shape, approximately 2.4mm thick, and can be stored in a wallet or card case. Additional Features: It also has a forgetfulness prevention notification function, a function to locate the SmartTrack Card by making it ring, and a function to make your smartphone ring from the SmartTrack Card. Supported OS: Compatible with the "Find My" network on iPhone, iPad, and Mac devices. Power: Built-in battery (non-replaceable), with a battery life of up to 3 years.