the same mass range for the outer radial bin. The low-mass end of the MF by [@Mand96] ($M/\Msun<0.4$) has a slope of $x=1.6\pm0.1$.

The level of mass segregation of M55 is comparable to that found in by [@Richer89]. M71 shares with M55 similar structural parameters as well as positional parameters inside the Galaxy. The detailed analysis of [@Richer89] of M71 showed that this cluster should also have a large population of very low mass stars ($\sim0.1$).

By fitting a multi-mass isotropic King model [@King66; @GG79] to the observed star density profile of M55, we compared the observed mass segregation effects with the one predicted by the models. Here we give a brief description of our assumptions in order to calculate the mass segregation correction from multi-mass King models. A more detailed description can be found in [@Pryor91], from which we have taken the *recipe*. The main concern in the process of building a multi-mass model is in the adoption of a realistic global MF for the cluster. For M55 we adopted a global MF divided in three parts:

-   a power-law for the low-mass end, $0.1<M/\Msun\le 0.5$, with a fixed slope of $x=1.6$ (as found by Mandushev   1996);

-   a 