Check the listing for details. TrolMaster Hydro-X Dry Contact Station DSD-1. Condition: New. Listed at 74.95 USD. Price is for (1) Trolmaster (DSD-1) Dry Contact Station（DSD-1）The Trolmaster DSD-1 Dry-contact module provides a simple and flexible solution to who want to connect & control devices to the Hydro-X using a “dry-contact” or relay to activate the device. Some equipment requires either normally open or normally closed contact closure in order to activate the equipment. The DSD-1 is the product that you need to control those types of devices. *The DSD-1 can be configured to work as the other Trolmaster power modules work. The DSD-1 connects into the “devices” line on the Hydro-X and can be set to control an almost infinite number and types of devices such as:Lighting contactorsLight Deprivation curtainsPump contactorsTemperature devicesHumidity devicesCO2 devices