Micro GBP /M6B is the futures contract for the GBP/USD exchange rate. This is called a “micro” futures contract because it is one tenth the size of the standard GBP/USD futures contracts The micro futures contract size is 6,250 British pounds (and the standard one is 62,500 British pounds). So if GBP/USD exchange rate is 1.4000 then micro contract size in USD is $8,750 – that is 6250 GBP x $1.4000. Current prices are here.