Spectroscopic observations of the low-mass eclipsing binary NSVS 11868841 have been obtained and the radial velocities were derived for both components .
The masses and radii determined for the components are M _ { 1 } =0.870 \pm 0.074 M _ { \odot } , M _ { 2 } =0.607 \pm 0.053 M _ { \odot } and R _ { 1 } =0.983 \pm 0.030 R _ { \odot } , R _ { 2 } =0.901 \pm 0.026 R _ { \odot } .
Both the primary and secondary stars ’ radii are 10 % and 57 % larger than those of zero-age-main-sequence stars with the same masses .
This discrepancy may be arisen from the large spot coverage of both stars .
We collected absolute parameters of 21 low mass double-lined eclipsing binaries and compared their positions in the mass-radius and mass-effective temperature panels .
The large radii and lower effective temperatures are solved neither with difference in metallicity nor in mixing length parameters .
These discrepancies in the low mass stars may be originated by magnetic fields causing inhibition convective energy transport which leads to large magnetic spot coverage on the surface of a low mass star .