So many kinds. Some are attached to the reloading tool, some hand held. Some are dedicated to just putting in a new primer. Again the key thing is that your are using the correct primer. The primer pocket has to be in condition to accept the new primer.
Many folks get automatic primer feeds.
Bit complicated to explain here, but the device picks up a new primer and puts it in the right place to be inserted in the next case. I am partial to doing it with a hand held tool as I really want to examine each and every case both inside and outside before the next stage. The auto types will keep you from handling each primer and generally quickens the process. Be aware that primers are dangerous. Keep them in original containers.