Now that Cisco no longer ships console cables with their devices by default (unless ordered at the time of purchase), you may find yourself without a console cable or at some point find the tab on the RJ45 adapter has broken off. With the 3 parts you see below, you will always have what you need for a console cable. The only thing you will have to add and will find far easier to locate is a standard ethernet cable. Finding a properly wired rollover cables is nearly impossible. What follows are my affiliate links to Amazon so that you can put your own console cable together like I use.
This plug converts the RJ45 connector to the pinout required on a serial port. You can still find some of these laying around at a company who has purchased Cisco gear for years but Cisco has long since started going to the completely molded DB9 to RJ45 cable. If you happen to have a supply of the properly pinned out rollover cable (different from an ethernet or crossover cable), that you only need the first two items shown here.
This last item is what can end up being the magic sauce in a DIY console cable. It allows you to take a standard garden variety ethernet cable and make the cable appear to the DB9 to RJ45 adapter above to be a properly pinned out console cable. The advantage with this little gem is that you can have a variety of lengths available to use instead of being limited to the length of the Cisco provided rollover cable. It also saves you have having to build your own rollover cable and keeping it with you. Let someone else build the cables !