What is the low-inventory-level fee?
A low-inventory-level fee will apply to standard-size products with consistently low inventory relative to customer demand. When sellers carry low inventory relative to unit sales, it inhibits Amazon's ability to distribute products across their network, degrading delivery speed and increasing their shipping costs.
In AZInsight Advanced, you can locate this fee by navigating to Settings > Calculator Settings, and then selecting FBA Low Inventory Fee.