From afar, this bridge appears to have gold railings/iron work.
The custom is to write the names of you and your loved one on the lock, lock it to the bridge and then throw away the key into the Seine. Thereby declaring that your hearts are forever locked together in love. Aw... sigh.
But the real question is.....
Are you cheating when you use a combination lock? That's not very committed now, is it?!?!?!