Suggested Part Numbers 19 19 Part Number Channels Output type Outputs Inputs Control Type Width 2 Voltage (SRR) 2 2 Standard 2 Voltage (SRR) 2 None Standard 2 Voltage (SRR) 4 None Heating and Cooling Control 2 Linear Current 2 None Standard 4 Voltage (SRR) 4 4 Standard 4 Voltage (SRR) 4 None Standard 4 Voltage (SRR) 8 None Heating and Cooling Control 4 Linear Current 4 None Standard