For Cummins ISX & Caterpillar 3400 Series. APPLICATION: Designed specifically for Cummins ISX QSX 15 and Caterpillar 3400, 3406, 3408, C15 engines with a 5.4″ bore. Our Heavy-Duty Piston Ring Compressor Tool is engineered for precision and reliability, minimizing the chances of errors during installation.