I have used this product since first going to Japan in 1997, where they were common in "hyaku-yen" shops. Hyaku means 100, making them cost about one dollar US.
However, they were imitation leather at that price and wore out in about a year due to the sewing giving way at the hinge.
These coin purses are very handy, fitting easily in a pocket and allowing you to see your coins and pick them up easily.
It also has a small pocket that is good for keeping a spare dollar bill or two.
I highly recommend them. You will get comments on them at check out stands everywhere admiring them and asking where you got such a utilitarian item.