Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to add some global industrial stocks to your portfolio, the iShares S&P Global Industrials ETF (NYSEMKT:EXI) could save you a lot of trouble. Instead of trying to figure out which companies will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The iShares ETF's expense ratio -- its annual fee -- is a relatively low 0.48%, and it recently yielded about 2.2%. The fund is fairly small, too, so if you're thinking of buying, beware of possibly large spreads between its bid and ask prices. Consider using a limit order if you want to buy in.

This ETF has performed reasonably, beating the world market over the past three years and inching ahead of it over the past five. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

With a low turnover rate of 6%, this fund isn't frantically and frequently rejiggering its holdings, as many funds do.

Why industrials?
The industrials sector will see demand grow once the world's economies get back on track. While there are some signs that that is happening, some fear that it won't happen soon enough.

More than a handful of global industrial companies had strong performances over the past year. 3M (NYSE:MMM) gained 21%. It's long been a dividend stalwart, paying shareholders for many decades, through good times and bad. It recently yielded 2.5%. The company, known for its innovation and diversification, has been growing at a slow and steady pace, and has been investing heavily in research and development.

Honeywell (NYSE:HON) also advanced 21%, performing well and expecting that to continue, though Boeing may deliver some challenges due to quality issues with its new Dreamliner plane and labor issues. Fortunately, this is a rather diversified company, with many other promising lines of business, such as even serving the smartphone market, wireless technology, and more. It also recently inked a $2.8 billion "lifetime" contract to supply Embraer E-Jets.

Eaton (NYSE:ETN) rose by 20%. The power management company has been shifting its focus from international projects to more U.S.-based ones. Management recently projected revenue growth of 42% in 2013 and that operating earnings will set a record. Eaton is also growing via acquisition, recently gobbling up Cooper Industries for more than $11 billion, which diversifies its offerings further. Analyst Stephen Simpson likes the Cooper buy, noting that it reduces Eaton's cyclicality. Eaton has also started seeing its inventories of heavy equipment start to shrink, which is promising. It yields about 2.5%.

United Parcel Service (NYSE:UPS), meanwhile, gained 12%. It recently upped its dividend by almost 9% and recently yielded 2.9%. On top of that, UPS is planning a massive share repurchase of about $4 billion this year. The company stands to gain from the U.S. Postal Service's struggles (though some are pointing out that the situation is not as it appears there). Even without that, though, online retailers are enjoying booming business, which translates into lots of deliveries for UPS and others.

The big picture
Demand for industrial goods and services isn't going away anytime soon. A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier.

Longtime Fool contributor Selena Maranjian, whom you can follow on Twitter, owns shares of 3M. The Motley Fool recommends 3M, Embraer-Empresa Brasileira, and United Parcel Service. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.