The GV-Relay V2 is designed especially for driving higher voltage output devices, and it is controlled by other GV devices, such as GV-Video Server, GV-Compact DVR, GV-IP Camera, GV-DSP LPR, GV-I/O USB Box and GV-NET/IO Card V3.1. The GV-Relay V2 provides 4 relay outputs, and each output can be set as normally open (NO) or normally closed (NC) independently as per your requirement.