Fentanyl doses in micrograms I believe. A lot of addicts are addicted to the feeling of the injection and the ritual of it as well.

Heroin I believe doses in the tens of mgs, which is hard to measure precisely but can be weighed on a twenty dollar scale. You could distribute fent in the same way Lsd is on blotter paper. The big difference is you accidently get a hot spot of Lsd it's not fatal.

Many addicts aren't buying massive quantities at once either nor are they getting it from the internet.