The Feltz is used in conversation, when one suspects other person(s) in said conversation have no idea what you are talking about, and are just agreeing with you because they do not want to look stupid, or they are generally just incompetent.
A positive Feltz is successfully dropped into a conversation unnoticed and unchallenged by other person(s), and positive confirmation of what you have said is received.
See also bullshit detector.
"Yeah, I've checked with our technical manager, and he said that hanging bar won't cope with your projector equipment, as it's only rated at 50 Feltz.
You'll have to use this one instead"
"Well, I can't argue with that, we'll have to make it work off this one"
This is an example of successful Feltz deployment.