A Pillbox is a Fortification counter which has some of the characteristics of the vehicles.
Operationally, a Pillbox is a vehicle with turret, without movement capacity, with a large armor, and located in a bunker hex with a strong protection by terrain effect (TEM).
It is not allowed to enter or exit a Pillbox hex.
The Pillbox has a main weapon that can only fire through the Covered Arc of the Pillbox.
From the Pillbox it is allowed to shoot at any adjacent hex, even if it is not inside its Covered Arc.
Reciprocally, it is allowed to shoot at a Pillbox hex from any adjacent hex, even if it is not within your Covered Arc.
A Pillbox counter must be placed with the gun pointing at a specific hex-spine so as to define the Arc Covered of the pillbox.
A pillbox can vary in size and type of construction as defined by the Strength Factors on the counter.
A pillbox may contain one (but not more that one) Gun.
No vehicle, Personal, or animal may occupy a pillbox.
A pillbox is not an obstacle to LOS.
LOS from inside a pillbox may be traced only within its Arc Covered.
In the attached image, hex A is a Bunker hex.
In the image, the hexes that are inside the Covered Arc by the Bunker are indicated in red.
From A you can not see (shoot) hex B because the obstacle of hex D blocks LOS.
Similarly, from hex C you can not see (shoot) hex B because the obstacle of hex D also blocks LOS.
The LOS is not blocked if from hex A it is fired into the "adjacent" hex D, and vice versa.