Power Solutions International (PSI) designs, engineers, and sells engines and integrated power systems, primarily to OEM customers who embed PSI products into their own equipment. PSI's engines run on natural gas, propane, biofuels, gasoline, and diesel, with roughly 74% of engines sold running on propane or natural gas. PSI serves three end markets: Power Systems (generators, microgrids, CHP, data center backup, oil and gas), Industrial (forklifts, agricultural equipment, construction), and Transportation (though PSI exited the on-road market in January 2024). PSI sources engine blocks from suppliers including HD Hyundai, Weichai, and others, then integrates them with fuel systems, electronics, controls, and other components to deliver a fully assembled, emission-certified power system — a single part number ready for OEM installation. This model lets PSI leverage aggregated procurement scale across its OEM customer base, reducing complexity for customers and creating sticky supplier relationships. PSI also manufactures certain engine blocks internally at its Illinois and Wisconsin facilities. PSI's aftermarket parts business provides recurring, higher-margin revenue as customers replace components over the life of PSI's power systems. Margins are driven by product mix, with PSI's heavy-duty natural gas engines (32L, 40L, 53L) carrying better returns. Weichai, which owns 46% of PSI's common stock, is PSI's most important strategic partner, providing access to R&D, manufacturing scale, and international distribution through Baudouin across Europe, the Middle East, and Africa.