  We discuss the 3-window modeling of cold, dense QCD matter equations of state
at density relevant to neutron star properties. At low baryon density, n_B < ~
2n_s (n_s: nuclear saturation density), we utilize purely hadronic equations of
state that are constrained by empirical observations at density n_B ~ n_s and
neutron star radii. At high density, n_B > ~ 5n_s, we use the percolated quark
matter equations of state which must be very stiff to pass the two-solar mass
constraints. The intermediate domain at 2 < n_B/n_s < 5 is described as neither
purely hadronic nor percolated quark matter, and the equations of state are
inferred by interpolating hadronic and percolated quark matter equations of
state. Possible forms of the interpolation are severely restricted by the
condition on the (square of) speed of sound, 0 < c_s^2 < 1. The characteristics
of the 3-window equation of state are compared with those of conventional
hybrid and self-bound quark matters. Using a schematic quark model for the
percolated domain, it is argued that the two-solar mass constraint requires the
model parameters to be as large as their vacuum values, indicating that the
gluon dynamics remains strongly non-perturbative to n_B ~ 10n_s. The hyperon
puzzle is also briefly discussed in light of quark descriptions.
