Touch Plate 4 Wire Low-Voltage Relay.Single Pole Single Throw Mechanical Latching Function. Rated 120/277/347 VAC, 20 Amps. Replaces Older Models 1550-B-PL and 2500-BPL Types. The Only Physical Difference Is The Size Of The Relay Base. The 4000-PL And 3000-PL Relays Are About 1" Larger In Size. THIS ITEM IS OBSOLETE. Please Order Item Number 3000PL Which Is A Direct Replacement