Zoro.com, the U.S.-based unit of W.W. Grainger’s online-only Endless Assortment segment, which caters to “smaller customers with less complex operations,” has reached the $1 billion sales mark.

“Zoro exists to make our customers’ lives easier, and this achievement is a testament to the ways we continue to help small businesses find and buy more of what they need in one place,” says Zoro.com president Kevin Weadick. “There is nothing but opportunity for Zoro to continue to grow.

Zoro’s sales shot up 27.4% to $276 million in the third quarter, up from $217 million a year earlier.  Helping to drive that growth were continued increases in the number of Zoro’s registered customers, to more than 4.4 million, and its number of available SKUs, to 10.3 million, Grainger said.

In a recent earnings call, Grainger, the biggest public distributor of maintenance repair and operations (MRO)products, attributed ecommerce growth in large part to Zoro’s 10% increase in its number of SKUs to more than 10 million. It also attributed it to its competitive position in selling to business customers not targeted by other sellers of MRO products that companies used to operate their facilities.

“We’ve seen nice increases in average order value” at Zoro, Grainger CEO DG Macpherson said on an earnings call. “We expect that to continue to get a little better as we continue to refine our processes to get more repeat business from those business customers.” Macpherson added that Zoro was increasing its number of large customers as well as its core market of small and midsized companies.