I’ve looked at -> this tutorial before on several occasions and I find it to be the most comprehensive on this subject matter. Old Kodak Brownie cameras (like the Duaflex that’s on my desk) accept out of production 620 film. Luckily for us camera fanatics, it is possible to re-spool 120 film on old 620 reels. 120 film is essentially the same as 620, just the reels are of different dimensions. People speculate that these two sizes of reels were developed to increase competition between foreign and domestic manufacturers. Whatever the case, it will be a joyous occasion when I take my Duaflex out to shoot for the first time. REMEMBER that if you decide to try this, you NEED to be in total darkness!