Jersey Mike's features 12 types of cheesesteak sandwiches, and with every iteration of the original Philly cheesesteak, one thing remains the same: the cooked-to-order steak.
You'll have to dig deep to find any meat-sourcing information on Jersey Mike's website. Nutritional information simply lists "beef" as the main ingredient in the Philly beef.
Since 2015, Jersey Mike's has simply stated it uses "privately-labeled meats and cheeses" and prioritizes brands with high-quality standards and very reputable practices.