These spring loaded test probes (sometimes called pogo pins) are commonly used for In-circuit testing of printed circuit boards and modules. We currently supply 2 types of the most commonly used test probes, a star headed pin that is used to mate with a 0.1″ PCB holes and a cup headed pin that can be used to mate with 0.1″ PCB header connectors. We also sell the receptacles (housings) for the test pins, allowing for easy replacement if the pin becomes damaged.