A reed relay is an electronic relay based on reed switch technology, which uses reed switches as contacts to achieve switching functions. According to different classification criteria, reed relays can be classified into the following categories:

Single pole single throw (SPST) reed relay: with one contact, it can achieve switch control of one signal.

Double pole double throw (DPDT) reed relay: With two contacts, it can achieve simultaneous switch control of two signals or dual state control of one signal.

Three pole double throw (3PDT) reed relay: With three contacts, it can achieve simultaneous switch control of three signals or control of three states of one signal.

Four pole double throw (4PDT) reed relay: With four contacts, it can achieve simultaneous switch control of four signals or control of four states of one signal.

These are the most common classification methods for reed relays, and the specific type can be selected according to specific application needs. Dry spring relays are commonly used in switch applications that require high speed, high reliability, and long lifespan, such as in communication, automation control, and safety systems.