You get the pen and cartridges for the pen. With the cartridge it is 2 parts Diluent and powder together. Place the cartridge in the pen (unscrewed all the way) Screw them together ,you'll see the powder and diluent mix . Softly go from side to side until mixed . Put a needle on the pen. Click the pen 1 time to get all the air bubbles out. Your ready for the nicest HGH around. I have a Upjohn pen that is basicly the same type . You got a nice batch !