Seeed Studio 4-Channel SPDT Relay HAT for Raspberry Pi is a solution for controlling devices that cannot be directly controlled by the I2C bus. This HAT utilizes four high-quality Single Pole – Double Throw (SPDT) relays and provides Normally Open/ Normally Closed (NO/NC) interfaces that control the high current load. The SPDT relay HAT operates from 4.75V to 5.5V input voltage range, 15A maximum switching current, and is available in 91.2mm x 56mm x 32mm dimension.