When purchasing jet skis in bulk, you must prioritize engine displacement (measured in CCs) and cooling systems. Look for Closed-Loop Cooling Systems (CLCS), which prevent corrosive saltwater from entering the engine, significantly extending the product's lifespan. Additionally, verify the hull material; high-impact ABS or SMC (Sheet Molding Compound) is preferred for its balance of weight and durability. Ensure the horsepower (HP) ratings align with your target market's skill level, ranging from 60 HP for rentals to 300+ HP for performance models.