There is constant inter-office trading. A relatively small yet important portion of trading is still done by open-outcry in the Ring. There are a morning and an afternoon trade, where each of the nine metal contracts are traded in two blocks with a five-minute session for each contract (the sessions last from 11.40 until 13.10 and from 14.55 until 16.15, each session includes a 10-minute break). The second trading block in the morning is key to setting the Daily Official Exchange rates. After the official trades of sessions one and two, there are 85 and 45 minutes of "kerb" trading respectively. Trades are in futures, options and TAPOs (traded average-price options, a form of Asian options).