Yep, the so-called "La Spezia" or "Mediterranean" turret, a conning tower conversion usually carried out in the shipyards at La Spezia (hence the name), which consisted in an enlarged flak platform to host two additional 13.2 mm Breda twin-machine guns. They were stowed in pressure-tight containers on the wintergarten. The 20 mm gun was retained but moved farther aft.
U-81 (Breda twin-guns in pressure-tight containers and 20-mm gun)
U-81
U-83
U-596
U-73
