Mill Rock Packaging, a growth and operations oriented private investment firm, completed the acquisition of Keystone Paper & Box Company, a specialty packaging company that manufactures custom folding cartons for consumer and healthcare end markets. Financial terms were not disclosed. "I am very proud of what we've achieved at Keystone since our founding by my grandfather. Through our partnership with Mill Rock Packaging, our customers will gain access to high-quality production facilities in the Midwest and West Coast. I am delighted that Mill Rock Packaging shares our commitment to quality, integrity and service, and I look forward to future growth leveraging our combined resources," Jim Rutt, Keystone President.