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 series machines. These locomotives were procured because the right design was sought for the routes with many bends and gradients. Fairlie locos basically consisted of two backwards-connected engines and thus had two boilers with two complete engines that worked independently and had to be operated simultaneously by the fireman.

This type of construction was particularly suitable for the narrow radii, since the running gear was mounted on bogies and thus allowed a great deal of freedom of movement. However, the operation presented a very big challenge, at least for the second man, since he had to load and control both fireboxes at the same time. Added to this was the tight space in the driver's cab, which hardly allowed freedom of movement.

Mainly for the latter reason, no further II K were procured 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 the first engine was retired in 1903 and the second in 1909. Four years later, a new double locomotive was built from two times two pieces of the 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.