Abstract: The present application pertains to a swivel insertable into a casing ram. The swivel comprises an inner mandrel having an upper end section and a lower end section configured to be operably connectable and rotatable with an upper workstring section and a lower workstring section, the inner mandrel comprising a longitudinal passage forming a continuation of a passage in the workstring. An outer housing is configured to seal the inner mandrel inside the outer housing. The outer diameter of the outer housing and the length of the outer housing is configured to fit a casing ram. In contrast to prior art tools placed within annular blowout preventers which have limited differential pressure ranges, the instant device allows for differential pressure during operation as high as 10,000 psi or more. The instant devices also may allow for aggressive frac pack treatments and facilitate reverse out operations.