Knee Lifter Complete For Singer Industrial Sewing Machines. Part # : 2777 For Singer models : 31 Class, 95 Class, 96 Class Part # : 2777 For Singer models : 31 Class, 95 Class, 96 Class Knee Lifter Complete For Singer Industrial Sewing Machines. Part # : 2777 For Singer models : 31 Class, 95 Class, 96 Class