A Renko Double Bottom forms when two columns of black bricks reach about the same low, separated by a rebound. Renko charts are built from bricks of a fixed size that ignore time and small price moves: a white brick is added when the price rises by one brick size, a black brick when it falls by one brick size. The equal lows mark support, and the pattern turns bullish when the price rises above the rebound high; a move through the lows instead is a breakdown.
