Ingeniously applying cutting-edge technology: along
the whole profile length, a groove stretches in all four insides of
the window frame, into which the necessary fittings can be snapped
and screwed together in any place-yet the groove remains invisible!
A thin plastic "membrane" keeps it sealed, being penetrated
only where the fitting is meant to be during installation. The result:
smooth, convenient to clean surfaces all around, no dirt that could
collect inside a groove, nothing unsightly perturbing the balanced
profile shape.