Drive belt tensioning roller.

To fit:
Boxster (986) 2.5-2.7 1997-2004
Boxster (986) S 3.2 1997-2004
Boxster (987) 2.7 2005-2008 Tiptronic only
Boxster (987) S 3.2-3.4 2005-2008 Tiptronic only
Cayman (987C) 2.7-3.4 2006-2007 Tiptronic only
911 (997) 3.6 2005-2008 Tiptronic only

This part number supersedes older part numbers:

- 99610211754, 99610211756