It is the signer application that enables a device to generate digital signatures based on reading a FINeID Finnish Citizen Card issued by the Population Register Centre (PRC, Väestörekisterikeskus). The card readers below can be connected either to an Android device or a PC, but that device must have the appropriate software installed.
The ACR38U ND microUSB or ACR3901U-S1 mobile Bluetooth card readers are suitable for use with the Android Suomi.fi app for generating digital signatures.
If you instead install Fujitsu mPollux DigiSign Client on your Linux, Mac or Windows PC, you can choose from a wider range of readers that will attach to a USB port - Thales Gemalto IDBridge CT30 desktop reader, Identiv SCR3310 V2 desktop reader, Identiv CL 2700RH a premium desktop reader, Identiv SCR3500-A and Identiv SCR3500-C (with a USB-C connector).