Touch Plate 2 Wire Low-Voltage Relay.Single Pole Single Throw Mechanical Latching Function. Rated 120/277/347 VAC, 20 Amps. Replaces Older Models 1200, 1550-A, 1550-B and 2500-B Types. The Only Physical Difference Is The Size Of The Relay Base. The 4000 and 3000 Relays Are About 1" Larger In Size. THIS ITEM IS OBSOLETE. Please Order Item Number 3000 Which Is A Direct Replacement.