Barrel (unit) continued to use the same size barrels. In the worldwide oil industry, an oil barrel is defined as 42 US gallons, which is about litres or 35 imperial gallons. Oil companies that are listed on American stock exchanges typically report their production in terms of volume and use the units of bbl, Mbbl (one thousand barrels), or MMbbl (one million barrels) and occasionally for widest comprehensive statistics the Gbbl (or sometimes Gbl) denoting a billion. There is a conflict concerning the units for oil barrels (see ). For all other physical quantities, according to the International System of Units, the
Barrel racing course after time begins. Contestants cannot be required to start a run from an off-center alleyway, but contestants are not allowed to enter the arena and "set" the horse. It is required that the arena be "worked" after twelve contestants have run and before slack. Barrels are required to be fifty-five gallons, metal, enclosed at both ends, and of at least two colors. Competitors in the National Barrel Racing Association (NBRA) are required to wear a western long-sleeved shirt (tucked in), western cut pants or jeans, western hat, and boots. Competitors are required to abide by this dress code beginning