Arbitrage window means that there is arbitrage opportunity, that is, there is still profit after deducting all expenses. For example:
The price of copper is $6200/ton. Including exchange rate, freight and customs declaration, the CIF price is 60,000 RMB. If the domestic price is 6 1 1,000 RMB and the profit is 1 1,000 RMB, there will be arbitrage opportunities.