On the basis of slit spectra obtained with the SCORPIO spectral camera attached to the 2.6 m telescope of the V. Ambartsumian Byurakan Astrophysical Observatory (Armenia), MK classifications for 30 visual binaries comprising mostly late K and M type stars are presented. Comparison with other determinations shows that this configuration provides a reliable MK classification. Dynamical masses for 25 systems are computed. Using standard mass-luminosity calibrations, individual mass sums for 11

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... s consisting of virtually single, nonvariable dwarfs are calculated, showing a good agreement with corresponding dynamical masses. The dynamical parallax of HIP 112354 is closer to the trigonometric parallax given in the Yale General Catalogue of Trigonometric Stellar Parallaxes (van Altena et al.) than to the Hipparcos parallax.