First, please see u tube video link which will describe the proper way to reconstitute it which can be found on the following u tube video link below: https://youtu.be/Q54F5waIyLQ It explains how to reconstitute the 12 mg Pfizer Genotropin without the pen device to administer each dosage. The cartridge contains 1.0 ml of bacteriostic water and 12 mg somotropin powder (Total 36 units per reconstituted cartridge. Since it contains 1 ml water, and there are 36 units once reconstituted, the following equation should give you a good approximation of a 3 unit dosage, given 100 or 50 tick marks on either a 1ml insulin syringe or a half ml syringe, respectively. (100 × 3) / 36 which equals about 8.3 tick marks per 3 units. I wanted to thank Napsgear for their exceptional customer support and it was delivered discretely as fast as fast as 2 weeks once the tracking number was listed. I've been both referring Napsgear to others for almost 10 years now. They have never disappointed me as far as authenticity and Napsgear has always kept their word from the ordering stage to it being delivered. Thanks again. I'm looking forward until next time!