Looking for such adapters for my new phone with Type C USB port, I noticed that several adapter and cable ads mention a built-in 56K resistor that is supposed to serve fast charging. I wonder if it's really needed and what happens when one uses fast chargers without such resistors or slow chargers with them as I am not familiar with the underlying theory here. Basically I want to get adapters not only for fast charging but also for fast file transfer between the phone and a PC's USB3 port, though I'm not sure that Type C USB can even match the speeds possible with USB3.
Can anybody comment on this issue?