Either pen uses a dial on the base to select the dosage. Both pens deliver in half units and full units, so it is possible to deliver, say 2.5 units of insulin. To use, you simply dial up the dose, then push the base of the pen in with your thumb. Easy peasy.
The business end of the pen uses what is called a pen needle, a specially designed short needle that screws onto the tip of the pen the way you screw the cap back on your car’s tire after checking the air pressure. Needles come as thin as 33 gauge and as short as 3/16 of an inch. That’s very, very small.
The pen lasts for years. The penfill lasts a couple of weeks to a month. The pen needles last between a day at the most and a single shot at the least (depending you your insurance and bank account balance).
Novo’s NovoPen Junior is slim and painted in bright funky colors to make it kid-friendly. Lilly’s HumaPen Luxura HD is a bit larger, in forest green, and has a mechanism that reminds me of a Swiss watch or German camera: solid and mechanically perfect.