This double-sided Mega kit replaces Caterpillar kits: 4C-4788, 4C-4784, 4C-5859, 4C-8253, 9S-3135 and 4C-4782. 83 SIZES 633 O-RINGS 45 D-RINGS. Contents of Kit: 8 sizes Orfs o-rings 11 sizes SAE flange o-rings 13 sizes standard Boss o-rings 10 sizes metric port o-rings 9 sizes d-rings for XT5&6 flange connections 32 sizes yellow silicone o-rings. We promise to provide the best, highest quality o-rings and kits available at a fair price. Our o-rings will meet or exceed OEM specifications and we'll get them to you as fast as we possibly can. It's been happening for as long as heavy equipment has been a crucial part of job success - equipment breaks down on a job because of a bad o-ring. Delays cost tens of thousands of dollars in lost time because of a part that costs a few dollars. Quality Pac was formed more than 40 years ago to reduce the cost of o-ring related delays. We are committed to the goal of keeping low-cost part failures from causing big-dollar delays. We've spent thousands of hours talking to heavy-equipment parts and service managers, and working in the field, to be sure we can live up to our promise and meet our mission. Today, Quality Pac is one of the most value- and service-driven providers of o-rings and o-ring kits in the United States.