Review on Heat Erasable Fabric Marking Pens with 16 Refills for Sewing Quilting Dressmaking - 4 Assorted Colors Pack - Ideal for Marking on Fabrics/Leather, Complete Professional Tailors Tools Kit by Morgan Gilmore

2 of the 4 pen cartridges were not working (black and white). When I took one apart to replace with a new cartridge, the end that was removed to replace the cartridge broke in half. I tried more cartridges - there were a total of 6 bad cartridges including those that didn't work initially and those that failed when trying to replace them and ended up with 2 that worked. The other two pens (blue and red) worked great - hence 2 stars versus 1. Don't know if the bum has red and blue cartridges as I didn't have to check. But I suspect they will. I love how well the ones that work work! I will look for more reviews. I asked for a refund instead of replacing this product.