The Basic high speed lockstitch machine, easy to use for all standard applications. Uncomplicated proven technique wherever sewing at this level is requested.
The series 251-140042 is available in three different versions:

251-140042 for universal use in light weight to medium weight material, for shirts and all kind of garments.

With maximum sewing speed up to 5000 stitches/min, maximum stitch length up to 5 mm

251-140042 A for very light weight material e.g. such like silk.
With maximum sewing speed up to 4000 stitches/min, maximum stitch length up to 4 mm. 

251-140042 H formedium to heavy weight material e.g. in work wear and jeans

With maximum sewing speed up to 4000 stitches/min, maximum stitch length up to 5 mm.