I'm going through some old family photos with my Dad and have come across a small package in an odd print size. The folder is labeled "Exclusive Sun Ray Drug Co. Pocket Size Foto-Folio, The Personal Album of Double Size Prints". It contains three deckle edged prints 5 1/4 inch by 2 15/16. The prints are dated 1949 and the folder has an ad on the back for 620 Verichrome. Can anyone guess what film format these would have been from?