The world famous Dabbawallas of Mumbai, who had once caught the fancy of Prince Charles for their super-efficient Tiffin-delivery system, today shared the tricks of their trade with the US Commerce Secretary Gary Locke.Locke met the Dabbawallas near Churchgate station where they gather daily before delivering Tiffin boxes to their clients and had a chat with them about how they function.Sopan Mare the president of Nutan Mumbai Tiffin Box Suppliers said that they explained to Gary Locke their modes of delivering Tiffins: by trains, bicycles or carts, as they dont believe in using modern methods or technology. He said that they also explained the unique colour code system which ensures tiffin boxes reach the correct destinations, without confusion or delay.Around 5,000 dabbawallas deliver Tiffins to over two lakh clients across Mumbai every day. Locke, along with a delegation of representatives of 24 US companies, is currently on a visit to India.