Envelopes technical Indicator is formed with two Moving Averages one of which is shifted upward and another one is shifted downward.

Envelopes define the upper and the lower margins of the price range. Signal to sell appears when the price reaches the upper margin of the band; signal to buy appears when the price reaches the lower margin.

To avoid a spontaneous entries one may use this update from Envelopes Indicator = Envelopes-Stepper.