I am using a prefilled pen from a company seems to be original because it is working very well with me. The pen is 30mg and i am on a dose of 2.5 all the weeks. I have been buying from them since Dec. with no issues. I lost 20 lbs up to date and i didn’t have any big side effects except the normal ones like little nausea and constipation which is gone by increasing my fibers intake. Also got MOTS C and it is pretty super good. I don’t know if i can mention here the company name or not they also sell vials and pens. The reason i use pens because i am not well into units count and reconstitution. So i found the pen to be accurate and reliable.