Check the listing for details. Ecolink WST-220 Recessed Wireless Door Sensor- DSC Compatible 433MHz. Condition: New. Listed at 39.99 USD. Ecolink WST-220 Recessed Wireless Door Sensor- DSC Compatible 433MHzAdvanced Security LLC offers UL Alarm Monitoring Services starting at $15.00 per month or DIY Self-Monitoring Services starting at $10.00 per month, NO Contracts, NO Hidden Fees, & NO Activations Fees. Message or visit our websiteWe are an Authorized Alarm DC, Honeywell Home, Resideo, AlarmNet, Ecolink, DSC, Telguard, SecureNet, Uplink, Alula, Bosch & 2GIG Security Dealer. We only sell Genuine Products, from authorized distributors. Not closeouts or old stock.Ecolink WST-220 Recessed Wireless Door Sensor- DSC CompatibleEcolink’s Wireless Recessed Door Contact is the ultimate in discrete protection. Mounted inside the door or frame, this sensor is invisible when the door is closed.• Compatible with DSC 433MHZ• Proven reliable wireless technology• Only choice for discrete protection• 2.5” x 0.75” diameter• Replaceable lithium battery (CR2)• 5 year battery life• 1.0” magnet gap• FCC and IC approved