It's the one that is supposed to held a pack of cigarettes, about 65 x 105 x 30 mm (outside measures).

[editing ...] I check on Witz web site : I guess it's the Keep-it Safe model, compact size = 2.7" Wide x 4.3" High x 1.3" Deep. Those are outside measures, including the lanyard hole
[end editing]

The Keep-it Safe FAK model was not available where I bought my boxes.
Anyway, I guess the nice white cross would easily and rapidly wear off

Alain