Connection used with laptop network and modem PC Cards. The XJACK connector is a small plastic piece that can be extended from inside the card. The plastic piece has a hole that allows the RJ-11 or RJ-45 connector to plug into it. The picture shows a 3Com OfficeConnect 10/100 LAN PC Card, with the XJACK connector extended on the right side of the card. Although this connection is easy to use and does not require an external cable or dongle, if users are not careful, the plastic piece can break off easily.