Class II K consisted of two Fairlie locomotives built by the British firm R. & W. Hawthorn for the Saxon narrow gauge railways. Their design made them unique among the German railways, but their blatant defects prevented the procurement of more locomotives. These locomotives were ordered in search for a fitting design for lines with many curves and gradients. Fairlie locomotives basically consisted of two locomotives connected back to back and thus had two boilers with two complete engines that worked independently and had to be operated simultaneously by the crew.

This design was particularly suitable for the narrow curves, since the running gear was mounted on bogies and thus allowed a great deal of freedom of movement. However, their operation presented a very big challenge, at least for the second man, since he had to fire and observe both fireboxes at the same time. Added to this was the tight space in the cab, which hardly allowed freedom of movement.

Mainly for the latter reason, no further II K were ordered and instead the III K was developed. It was also stated that the weight was too high for the existing lines. Both prototypes remained in service until they were withdrawn in 1903 and 1909. Four years later, two new double locomotives were built from four I K, which were also given the designation II K. Before being named II K or K II, the locomotives were called Htn F TK, from which the characteristics of these locomotives could be derived. Htn stood for the manufacturer Hawthorn, F for Fairlie, T for tank locomotive and K finally designated all locomotives for 750 mm gauge.