Advance Auto Parts is a leading auto-parts retailer in North America with more than 4,000 store and branch locations. About half of the firm's sales are geared toward the professional channel, with the remaining sales in the do-it-yourself market. Through its vast store footprint and distribution network, Advance manages thousands of stock-keeping units for various vehicle makes and models. The retailer primarily competes on the basis of inventory availability and service speed, making the operating efficiency of its hub-and-spoke distribution model critical to meeting customer needs.