Dover QuadHorizontal section at the level of the embrasures. Pillbox Type Dover Quad. Note square plan with wide embrasures. The extent of the overhanging roof shown as a dotted line.
The Dover Quad pillbox is a 13 feet (4.0 m) square pillbox with wide embrasures and an overhanging roof slab. This design is only found in the Dover area of England and are very often found at high commanding positions. Some commentators opine that the Dover Quad is a poor design: the overhanging slab, while offering some protection from strafing, is liable to ricochet bullets from below into the embrasure which is, in any case, wide giving inadequate protection. Given the vulnerability of the port of Dover, it is possible that these were among the first World War II pillboxes constructed and they may have pre-dated the FW3 designs, but there is no evidence for this.