Abstract: A blowout preventer includes a main housing containing a through bore. A first chamber is arranged transverse to the through bore. A second chamber is transverse to the through bore and is diametrically opposed to the first chamber. A first shearing device is located in the first chamber and a second shearing device located in the second chamber. The blowout preventer includes a charge that when activated propels each shearing device along its respective chamber and across the through bore into the opposing chamber, such that the first and second shearing devices are adjacent each other.