  Physical parameters of both the mass donor and compact object can be
constrained in X-ray binaries with well-defined eclipses, as our survey of
wind-fed supergiant X-ray binaries (SGXBs) IGR J16393-4643, IGR J16418-4532,
IGR J16479-4514, IGR J18027-2016 and XTE J1855-026 reveals. Using the orbital
period and Kepler's third law, we express the eclipse half-angle in terms of
radius, inclination angle and the sum of the masses. Pulse-timing and radial
velocity curves can give masses of both the donor and compact object as in the
case of the "double-lined" binaries IGR J18027-2016 and XTE J1855-026. The
eclipse half angles are 15 (+3,-2), 31.7 (+0.7,-0.8), 32 +/- 2, 34 +/- 2 and
33.6 +/- 0.7 degrees for IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR
J18027-2016 and XTE 1855-026, respectively. In wind-fed systems, the primary
not exceeding the Roche-lobe size provides an upper limit on system parameters.
In IGR J16393-4643, spectral types of B0 V or B0-5 III are found to be
consistent with the eclipse duration and Roche-lobe, but the previously
proposed donor stars in IGR J16418-4532 and IGR J16479-4514 were found to be
inconsistent with the Roche-lobe size. Stars with spectral types O7.5 I and
earlier are possible. For IGR J18027-2016, the mass and radius of the donor
star lie between 18.6--19.4 $M_\odot$ and 17.4--19.5 $R_\odot$. We constrain
the neutron star mass between 1.37--1.43 $M_\odot$. We find the mass and radius
of the donor star in XTE J1855-026 to lie between 19.6--20.2 $M_\odot$ and
21.5--23.0 $R_\odot$. The neutron star mass was constrained to 1.77--1.82
$M_\odot$. Eclipse profiles are asymmetric in IGR J18027-2016 and XTE
J1855-026, which we attribute to accretion wakes.
