I experienced so much trouble with this. I bought 4 cello butterflow simply pens at once before going to my exam. When I wrote 4-5 pages after which the pen stopped flowing ink. I thought this was a defective pen and took out another butterfow simply pen and used it. I wrote 5-6 pages more a same problem started. The pen became so rough to write and was not at all giving a butterflow like experience. My handwriting went from neat to worst. I found that all cello butterflow simply had same problem. Also the style of pen was very old and was not attractive to eyes. Also its value of 10 rupees is questionable according to the pen's quality and design.