The following cameras were designed to use series filters without the need for adapters:
Super Speed Graphic with 1/1000 shutter-Ser 6
Kodak Signet 80 all three lenses-Ser 5
Kodak Signet 50-Ser 5 Kodak Signet 40-Ser 5
Kodak Signet 30-Ser 5 Kodak Pony IV-Ser 5
Kodak Automatic 35 all models-Ser 5
Kodak Motormatic 35 all models-Ser 5
Sears Tower Reflex by Aires, Lever Wind-Ser 5 Contrary to the above posts, my Kodak Stereo camera was made to use Ser 5 filters and my Kodak Signet 35 was not. It has 26.5mm screw threads.
How do I know all this? I own all these cameras. Although photography was already my hobby when all these cameras were new, I bought them all used.
By the way, somewhere I have a Kodak notice that in the future Arabic rather than Roman numerals would be used to identify filter series.