Помогите перевести фразу "penta version "

контекст:
Furthermore, as a practical matter, the penta version of a group of brominated flame retardants called polybrominated diphenyl ethers (or PBDEs) is no longer used to treat any foams made in the United States because U.S. production of penta ended prior to January 2005.

спасибо заранее !