Authorized reproduction of the users / instruction manual for a Singer model 400w21, 400w22, 400w23. 400w24, 400w28, 400w29 and 400w33, a round bobbin sewing machine. It is described as a high speed, lock stitch sewing machine. This manual is NOT being reproduced from an original manual. The text is quite legible but the illustrations leave a bit to be desired.