Freight rate volatility is one of the most underappreciated risks in physical product businesses. During the 2021-2022 shipping crisis, ocean freight from China to the US West Coast hit $20k+ per container — a 10x jump that wiped margins for importers who hadn't hedged. Air freight as a backup is worth keeping in your model even if you never use it; knowing your break-even point at air rates tells you a lot about product viability.