By Matt Griswold, Plastics News Staff Fontana, California - Fontana-based Flex Trim Inc. is the latest plastics building products maker to join the portfolio of investment group Graham Partners Inc.The Philadelphia-based private equity firm will integrate Flex Trim into another of its holdings - Troy, Alabama-based HB&G Building Products Inc., a manufacturer of columns and speciality millwork. HB&G operates plants in Troy and Raleigh, North Carolina.Flex Trim products are made by pouring polyurethane into moulds. The products can be stained or painted. Flex Trim moulded profiles are manufactured at plants in Fontana and Garner, North Carolina.The flexibility of Flex Trim's products allows them to be rolled up and shipped in boxes, giving them a competitive shipping advantage over rigid profiles, said Josh Wilson, a principal with Graham Partners, in a 29 Aug telephone interview."Our No. 1 goal is to integrate the business with HB&G," Wilson said. "We feel we can improve the marketing of the products, and we feel it's very complementary with our existing products in the synthetic millwork category."This is all about growth."Graham bought cellular PVC millwork extruder Turnkey Millwork Inc. of Raleigh in June and made it part of HB&G.The private equity firm has more than $850 million under management, focusing on industrial companies with sales between $20 million and $350 million that participate in manufacturing niches.The purchase price was not disclosed."