2Pack 6.0Ah PCC685L 20V Battery Compatible with Porter Cable 20V Battery Replacement for Porter Cable 20 Volt MAX Lithium ion Batteries 20 Volt PCC685L PCC680L Rechargeable - - Amazon.com
Porter Cable 20V Max and 18V Batteries are NOT Interchangeable! - YouTube
Porter Cable 18V Tools - Upgrade to lithium batt | Bob Is The Oil Guy
FYI, Porter Cable 20V Max and 18V Tools and Batteries are NOT Cross- Compatible