Pritzker Group, the investment firm led by billionaire brothers Tony and J.B. Pritzker, agreed to buy flexible-packaging company ProAmpac from private equity firm Wellspring Capital Management.

The transaction is expected to close in November, according to a statement. The Cincinnati, Ohio-based manufacturer makes a wide variety of packaging products, from can liners to cheese laminates to bank deposit bags. Terms of the acquisition weren’t disclosed.

"Combining our permanent, proprietary capital base with this management team will enable ProAmpac to have tremendous opportunities for growth, both through organic initiatives and accretive acquisitions," J.B. Pritzker said in the statement.

Heirs to the Hyatt Hotels Corp. (NYSE: H) and Marmon Holdings Inc. fortune, the Pritzker brothers lead the Chicago-based Pritzker Group, which uses their long-term capital to acquire and operate middle-market North American companies. The firm also has a venture capital arm and an asset management unit.

The Pritzkers have embraced direct investing in companies, a trend that’s become increasingly popular among wealthy families that see value in side-stepping private equity firms’ fees and in holding stakes for longer than many funds. In 2015 direct deals by family offices returned about 15 percent on average, according to an April survey by the Family Office Exchange.