(FORTUNE Magazine) – Do you have a gas grill? Noticed how many propane tanks these days have stickers with little blue cartoon rhinoceroses? Well, maybe you should: Blue Rhino (RINO, $13), the company that makes all those tanks, has been charging ahead with a five-year annual revenue growth rate of 70%. It's the only national propane distributor and a primary supplier to Home Depot, Lowe's, and Wal-Mart. Blue Rhino exchanges customers' empty tanks with clean new ones at 28,000 locations nationwide, giving it 50% of the $400 million U.S. exchange market.

Though Blue Rhino makes grills and other propane-fueled appliances (it's the market leader in patio heaters), the biggest chunk of its revenue comes from gas exchange. CEO and founder Billy Prim invented the U.S. gas-exchange industry in the early 1990s, when he first experimented with the concept. Back then most people would refill tanks from local mom-and-pop shops. Wal-Mart got wind of Prim's operation and approached him to provide safe and cost-consistent fuel for the gas grills it sold.

Prim likens gas exchange to the razor-and-blade business. "It doesn't matter whose appliance people purchase. We would give them away like cellphones." The company has ridden the great U.S. barbecue boom: Americans bought more than nine million gas grills last year and will probably buy even more in 2003. Prim is also expanding his customer base with new propane-fueled items like the Skeeter Vac. The market for "mosquito elimination systems," as the company calls them, is hot, thanks to the West Nile virus scare. What shouldn't scare investors is sky-high fuel prices. Though RINO sank on a propane price peak in 2000, the following year the company instituted fuel-price hedges. With that control, consistent growth, and the fact that the company's stock has been flat for a year, investors might want to think about lighting up.

--Julia Boorstin