Actually the turret armor for ostwind is only 16mm.
The 23/25mm bothered me for some reason so I looked into it a bit more.
http://www.missing-lynx.com/panzerace.htm5- Armor thickness of the plates on the sides of an “Ostwind” turret was?
Answer: 16 mm
Score: 32% answered this question correctly.
This misinformation stems from data listed in the original Heeres Waffenamt Technishe Daten Blatt G318I as Turm 25 mm (rundum) for the Flakpanzer IV, 3,7 cm (and was copied from this source onto page 111 of the Encyclopedia of German Tanks of World War II). 25 mm is correct for the flat sides of a “Moebelwagen” superstructure (starting with No.46) but not for the turret of the Ostwind.
The correct data was found on an original turret drawing and original documents on mounting this same turret on a Pz.Kpfw.III chassis. The correct information was first published in Panzer Tracts No.12 in February 1998.