The Russell 1000 High Eff Defensive Mod is an index that tracks the performance of the 1000 largest companies in the Russell 1000 Index, with a focus on companies that have a strong track record of defensive characteristics, such as low volatility, low beta, and low debt-to-equity ratios. The index is designed to provide investors with a portfolio of stocks that have a higher probability of outperforming the broader market during periods of market volatility.