In the past, I have bought this item as a gift to my nursing students and they were on back order. In an effort not to have this happen again, I purchased 20 syringe pens at the same time. When it was time to give them to the students, the red dye had evaporated in over half of them and the pen lost all effect. the pens did write still. Unfortunately some of my students got this poor gift. I do continue to buy this item;however, I do it later and cross my fingers that the red dye (""ink"") will still be in the pen.