A straight through electrical spring probe has an elongated resilient thin wall tubular member slit along the entire length thereof and comprises, in the wall, a transversely enlarged portion and a transversely inwardly extending stop. An elongated plunger member is telescoped in the tubular member and...http://www.google.es/patents/US4200351?utm_source=gb-gplus-sharePatente US4200351 - Straight through electrical spring probe
