The Keltner Channel is a volatility-based indicator which makes us of the "envelope theory" and uses the range of high and low. Moving average bands and channels, like the Keltner Channels, all fall into the general category of envelopes. Envelopes consist of three lines: a middle line and two outer lines. Envelope theory states that the price will most likely fall within the boundaries of the envelope. If prices drift outside our envelope, this is considering and anomaly and a trading opportunity.