Jar 3 : A device run on slickline, coiled tubing, tubing or drill pipe that will sharply increase the impact force of the conveyance when trying to retrieve a stuck tool or equipment
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}