Surge protective devices SPD Type 2 with thermal monitoring QuickSafe® are designed to protect against indirect lightning strikes and switching overvoltages. They are installed as close as possible to the supply point of the electrical system. All OVR T2 consist of a base unit and a replaceable protection module. They are equipped with a mechanical function indicator, and the TS variants come with a potential-free changeover contact. The variants with "reserve varistor" provide additional protection for the electrical system, as at the end of their service life, the surge protective device is not completely disconnected from the network; instead, a base protection is guaranteed by an additional varistor. This means that the system remains protected until the surge protection module is replaced. They are compatible with the System pro M compact series and can be connected to it via phase rails. Their primary application is in sub-distributions and final circuits.