Lug-Zilla, heavy duty power feeder set. 600V max rating. 2 per set

Use with AWG 14-10 gage wires to get reliable power to your rails.  You get one pair of code 332 direct-to-rail clamp modified to be Lug-zillas. No soldering needed, and easy to disconnect/reconnect. Best with SOLID wire. 
 
This heavy duty power feed is rated to 600V, more than enough to handle large scale trains.