I need cards printed on both sides. What equipment do I need to do that?

The easiest way is to purchase a dual sided or duplex printer. The printer will print one side, turn the card over and print the other side. The complete two sided card is produced in one print job.

You can also produce two sided cards with a single sided printer. For example, if all of the backs are the same they can be pre-printed beforehand and then loaded into the printer to have the front printed as needed. The other way is to print the front of the card and then manually turn the card over and re-load it to print the back.