Interiors of 152-mm battery firepost

Observation slit can overlap with armored shutters from the inside by means of ropes with handles, clearly visible in the picture.
These 152-mm guns were guarding the sacred borders of Sweden until 1977, until there were put into operation a new 120 mm guns, after which they were brought in a reserve. Part of facilities of 152-mm battery were used to house the 120-mm battery radar and laser rangefinder.