The Biotropin HGH Pen is user friendly, making your daily HGH administration accurate and leak-free as it is convenient. Activating the Human Growth Hormone pen is a simple process:1 - Insert a new  Biotropin HGH cartridge in the pen then place a disposable insulin needle on the end of the pen and tighten. Our pen uses a 32 G x 4mm needle. 2 - Unscrew the black dial at the end of the pen  until it's fully extended, then push down the dial firmly until it goes back to its original position. This step mixes the HGH powder with the bacteriostatic water. 3- Repeat this with the needle pointed towards the ceiling to avoid any build up of air in the system. Once reconstituted, the mixture will yield about 1 ml.4 - This time, slowly twist the black dial to the desired dose in IU as measured by the indicator at the  distal end of the pen. 5 - Inject the HGH subcutaneously on sanitised skin, by pressing down on the black dial.