Gold purchased and redeemed by gold ETF funds generally need to meet certain standards, otherwise the custodian will miscalculate the fund's net asset value due to the difference in gold fineness, which will lead to risks. The main gold ETF funds use the London commodity delivery bar recognized by the London Gold and Silver Market Association as the delivery standard, and the subscription and redemption of funds are based on gold bars that meet this standard, so funds and members can safely and conveniently deposit and redeem gold assets. This transaction form has greatly promoted the development of gold ETF.