This 55 Series Version Is Similar To 55 Series Model Of APFC In All Respects Except The Display, The Price And The Size Of The Controller. It Uses 2-digit 7-segment Bright Display For Power Factor Indication. Two Separate LEDs Are Used To Give LEAD/LAG Indication. It Is Smaller And Lighter In Weight Than The Regular 55 Series Model. This Low Cost Version Is Very Popular For Smaller Automatic Power Factor Correction Systems.