ok ive decided to switch to this hgh after using norditropin for so long , i got the 5.3 mg "16iu" catridges but without the pen so i have to use standard insulin syringe. can you please help me understand how it works like how can i measure 3 iu's , 4 iu. i tried reading all the guides i found even the sticky one on this one but its all different !!!