Stacked ceramic capacitors are multiple discrete multi-layer ceramic capacitors (MLCCs) terminated onto a common lead-frame for through-hole or SMT operations. They capture many of the inherent benefits of MLCC technology, like a low-loss material set, low ESR (equivalent series resistance), and higher reliability.
Typical applications like switch mode power supplies need larger capacitance values and current capabilities. Stacked MLCCs compete with discrete electrolytic capacitor technology in terms of capacitance range but have an advantage in terms of voltage and temperature capability, which naturally increases their reliability, thereby making this a preferred technology for defense applications despite its higher price point compared to electrolytics.