A catheter comprising a flexible tubing having a proximal end and a distal end. An electrode assembly is attached to the distal end of the flexible tubing. The electrode assembly includes an electrically conductive tip electrode and a coupler which is connected between the tip electrode and the distal end of the flexible tubing. The coupler and the tip electrode are coupled by an interlocking connection. A first magnet is at least partially housed in the coupler. A fluid lumen extends through the flexible tubing to the coupler. The fluid lumen extends completely through the first magnet and connects to at least one port formed in the electrode assembly. A second magnet is spaced from the electrode assembly along a longitudinal axis of the tubing. The first magnet and the second magnet are responsive to an external magnetic field to selectively position and guide the electrode assembly within a body of a patient.