Moving Average Envelopes (ENV) are a banded indicator. ENV displays an upper envelope above a basis line and a lower envelope below the basis line. The basis line is a moving average, either a simple moving average or an exponential moving average. The envelopes are set a (user defined) percentage away from the basis line. Envelopes are a good indicator for trend identification as well as identifying overbought and oversold conditions.
Read more about Envelope
in TradingView wiki.