The PAM00399 uses a case design that Panerai refers to as a 1940 Radiomir Case, apposed to the 1950 Luminor Case, which features the half-cresent trademark crown-gaurd, which Panerai originally referred to as the Tight Seal Device when they filed their American patent application in 1956 . Just to be crystal clear, the 1940 Radiomir Case has an 8mm winding crown, and the 1950 Luminor case has the larger, more protective crown guard which is the cornerstone of modern Panerai design.
It appears, with Panerai recently introducing the 1940s case, that they will keep going with it, and hopefully use it to bring back, what in my personal opinion is the most beautiful vintage Panerai ever made, the Reference 6154. The PAM00399 pictured above, comes pretty close to the 6154, and if it simply had an Arabic numeral 9, in place of the second hand, we would in effect have the most beautiful Panerai ever made.
Don't get me wrong, because I love the half-cresent crown guard found on the PAM00372, I just also love the minimalist design of the 8mm winding crown. Kind of like choosing between a vintage 1969 Lamborghini Mura, and a Ferrari California Spider ;-) Both are stunningly gorgeous, and I love them both for slightly different reasons.
Note: How can you tell which of the watches pictured above are vintage Panerai watches, and which one is a new model? The new models typically have an engraving on the front of the case, located between the lugs, and as you see in the photo above, the first watch has such an engraving, and the second two don't.
I LOVE the split lume bars on the minute hand on the PAM00399. This is an example of the detail that makes the Panerai design so outstanding...