Janome Serger Replacement Upper Blade Fits 204D, 504D, HD504D, 634D, 1110D & 888 The genuine Janome upper serger blade knife fits models 204D, 504D, HD504D, 634D, 1110D & 888. NOTE: It is recommended that you replace both blades when you replace the blades. Not doing so can damage the new blade.