The supply chain for a popular gaming console has the following structure:

Retailer gets product from a distributor, with a lead time of 3 weeks.

Distributor gets product from the manufacturer with a lead time of 5 weeks.

Manufacturer has a production lead time of 5 weeks.

The manufacturer keeps finished goods inventory, and wants to set the reorder point for this finished goods inventory. When finished goods inventory runs low (lower than reorder point) it takes 5 weeks to replenish as that is the production lead time.

What is the echelon lead time for the finished goods inventory at the manufacturer?