Dividends provide an additional source of income and returns in an equity portfolio, but investors should still know the type of exposure dividend exchange traded fund investments provide.

While high yield dividend ETFs generate attractive yields, the dividends may not be sustainable or the stocks could be more susceptible to market volatility. On the other hand, investors can take a look at stable “Dividend Achievers” that have a regularly increased dividends over the past.

For instance, the Vanguard Dividend Appreciation ETF (NYSEArca: VIG), the largest dividend ETF with $13.8 billion in assets, tries to reflect the performance of the Dividend Achievers Select Index, which tracks stocks that have raised their dividend in each of the last 10 years. Consequently, the fund has a heavy tilt toward mega-caps at 40.2% and large-caps 43.5%. VIG has a 2.24% 12-month yield.

=VIG also has a greater weighting toward consumer staples 26.5%, industrials 25.5% and consumer discretionary 12.2%. Meanwhile, the ETF also has a lower allocation in financials 6.3% and utilities 1.6%.

The ETF “seems to weed out companies with high leverage and poor cash flow,” according to Morningstar analyst Samuel Lee. “The result is quality rather than high yield, so income-hungry investors might be surprised by a dividend yield that just matches the market. Whereas many dividend-focused funds concentrate in smaller value companies, this fund shades slightly toward growth.”

Nevertheless, Vanguard also offers a high-yield ETF, the Vanguard High Dividend Yield Index ETF (NYSEArca: VYM), which recently had its expense ratio lowered to 0.10% from 0.13%. The fund only tracks U.S. dividend payers, excluding real estate investment trusts, excludes companies that did not pay a dividend in the past year and ranks holdings by yield. VYM has a 3.05% 12-month yield. [Dividend ETF Fee Cut: Popular Vanguard ETF Gets Even Cheaper]

For more information on dividends, visit our dividend ETFs category.

Max Chen contributed to this article.

The opinions and forecasts expressed herein are solely those of Tom Lydon, and may not actually come to pass. Information on this site should not be used or construed as an offer to sell, a solicitation of an offer to buy, or a recommendation for any product.