  We present simple models of N=4 supersymmetric mechanics with ordinary and
mirror linear (4,4,0) multiplets that give a transparent description of HKT,
CKT, and OKT geometries. These models are treated in the N=4 and N=2 superfield
approaches, as well as in the component approach. Our study makes manifest that
the CKT and OKT supersymmetric sigma models are distinguished from the more
simple HKT models by the presence of extra holomorphic torsions in the
supercharges.
