A little research led me to discover that John A Manson Company at 253 Broadway in Manhattan (stamped on these copper mounts) was a hardware store, established by Manson around 1910, with a citation in the Hardware Dealers Magazine in 1913 noting that price cards like these (sold via catalogue as well as at the store) were Manson's speciality. These two were certainly put to use, with the handwritten card on one detailing the sizes, costs and sale prices of a variety of "enameled ware", and the other showing a typed list of prices for sharpening various items, from axes to skates. These were covered with protective yellow translucent films, which kept them in great shape; there is a third list on the back of one that was not so lucky! 

I found these at an estate sale loaded to the gills with a lifetime's accumulation of all manner of things,  and think they'd be pretty cool hung in a hardware store one again, or in the kitchen by the kettle or pots and pans. Very much used and aged, as pictured, but the mounts are still super functional should one to slip some new lists into them.

Sold as a pair, as I found them, joined together with a wood and wire clip. 10"x 5 5/8" x 1/4" ea.