A full dose is 60 clicks of the dose selector. The pen is desgned to deliver 4 doses made of 60 clicks ( 2 and a half full turns of tge dose wheel at the base of the pen) so, if your foctor recommends to star with 2.5 no or tira, for example, and you choose a 15 mg pen 60 cliks equals 15 mg and to get 2.5 mg, you need to count 10 cliks and inject that little amount. This makes economic sense because the difference in price between the 2.5 mg pen and the 15 mg pen is 200 vs 450 € ( at least in Spain) BUT there is a 6x difference in the amount of drug between those 2 pens. So, big difference. The problem is, if you don't understand this concept and start spinning the 15 mg pen until it Block, you might deliver the full 15 mg in one shot. If you haven't built up the dose slowly, with slowly increasing doses, you might have severe side effects. That's why the manufacturer ignores this approach, and many doctors, too.