Singer Serger Machine Upper & Lower Knives #412585 & 412749 Fits Pro4D most 14u Singer 14U Serger upper&lower knife upper&lower knife Blades #412585,412749 knife for BABYLOCK SERGER - BL202, BL302, BL400, BL430 knife for Elna Serger T-3 ,T-33 ,T-34 ,T-34D PFAFF SERGER - 756