Block 3 of Castillon was equipped with two 75 mm guns model 1929. These guns had a range of 12.100 m. and a traverse of 45°. The guns of Castillon had to cover the area around Sospel. Block 3 is special in the way that the two guns aren't exactly pointed in the same direction. In fact there is a small angle between the axis of fire of the two guns to enlarge the total field of fire of the casemate.