are you talking about the chalk marker- or the chalkboard cloth?
i have one of the markers- and love it have been using it for 6 or 7 years now- all my friends think it's the greatest too--it is always close at hand.
as for is it ok to use??? guess it depends on what you want to use it for.
i use mine for all kinds of things. but if i'm going to mark a quilt for quilting with it i always test to make sure the color i'm thinking about using is going to come out- but i do that no matter what i plan to use...chalk, pencil, marker- what ever - if its somethhing i want to come out i check to make sure it's going to....i do not mark quilts for quilting very often- i use mine for marking diagonals on blocks--and lots of other things that are on the reverse side of the fabric-so it doesn't matter-
as far as i'm concerned not only is it ok to use- it's great to use---for the things i use it for.
i do not know who makes it- i bought mine from Clotilde's years ago