High Quality Content by WIKIPEDIA articles! W.B. Mason is a privately held large office supply contract retailer that competes with Staples, OfficeMax, and Office Depot. W.B. Mason primarily serves the New England and Mid-Atlantic areas of the United States. They have 29 distribution centers, roughly 1800 employees , 770 sales representatives, 376 delivery trucks (leased from Ryder ), and over 150,000 customers. It is one of the largest private office products dealers in the USA and one of the largest customers of United Stationers.