SkyBitz Inc., a Dulles developer of satellite tracking technology, closed an $18 million round of funding led by Industrial Technology Ventures LP and the investment fund sponsored by insurance giant American International Group Inc.

SkyBitz said the money will pay for marketing its shipment-tracking technology.

SkyBitz develops transmitters that use Global Positioning System satellites to keep track of shipping containers, tractor-trailers and the like.

Standard GPS receivers collect information from satellites and then compute their position. SkyBitz receivers relay the information from GPS satellites to computers that determine an exact position.

The process allows SkyBitz to make its tracking hardware smaller than most GPS receivers. It also consumes far less power.

SkyBitz, founded in 1995, spent five years developing its technology. It used government contracts for funding before raising $4 million in a first round of venture capital in July 2000 from a firm that is no longer in business.

For the second round, SkyBitz founder and president Matthew Schor wanted investors that not only were likely to be in business a long time but also understood his company's technology and could offer industry expertise and possible strategic partnerships.

AIG Highstar Capital, a fund sponsored by an insurance agency that partly specializes in transportation coverage, understood the value of tracking shipments easily and cheaply.

"It's certainly helped us understand the business and the market they were going after," said Michael Walsh, a principal with AIG Highstar.