It is not specifically designed for sewing, but many people do use it on material, and for a very good reason...
IT CAN BE ERASED WITH AN IRON!!!!!
How fantastic is that?!
Here is a little video I made using the pen demonstrating how unbelievable it is:
(I chose the demonstration fabric because it was cute, but just to let you know, it does already have little black flecks in it, and these weren't made by the pen)
I bought this as a 3 pack in the stationery aisle at the supermarket, for about £6. A while ago I'd been told about them by a quilter, but this week has been the first chance I've had to actually go into the supermarket and see them for myself. (We get our groceries delivered usually, so I do miss browsing the aisles)
Usually I use tailors chalk for dressmaking and a fade-away pen for crafty things, but sometimes the chalk doesn't go away until I wash the garment and every now and then I press too long with the fade-away pen and it doesn't fade away. Hopefully this will be my new go-to fabric marking pen.
Would be interested to know what marking tools you favour!
Please note: I bought these pens at retail price with my own money, I am not affiliated with this pen making company (nor the iron company) in any way, and these words are all my own observations.