They didn't transition to the Conrad/Barbasol style head until 45 maybe late 44, the old style also disappears at the same time. The Kant Rust comes into play around either 43 or 44 at the latest.
That's all true but not relevant to the reasonable contention that when the '45 ad says a "pre-war type" it simply means an all metal razor. I don't read it to suggest they are marketing the Cooper as an old razor. Sent from my Pixel 2 using Tapatalk
Pre-war can also mean a non Kant Rust style of razor. It is possible they made a plastic razor but I think the one on page 5 of the Cooper thread owned by @Jorvaljr is really a Sweedo because of the handle style.
Just sticking to the question of the '45 ad this looks nothing like the Kant-Rust and everything like the Conrad to me. In contrast here is the '41 Swee-do style razor. Sent from my Pixel 2 using Tapatalk
They made them concurrently in 45. The old style refers to just that the style which is visually distinguished by the handle not the heads especially in print ad.
We'll have to agree to disagree. To me its pretty clear what the ad is selling which is the pictured all metal razor not the Kant-Rust. Obviously the Kant-Rust was also marketed separately. Sent from my Pixel 2 using Tapatalk