Shear Ram BOP (Blind/Shear Rams)
Rams having cutting blades that will shear tubulars that may be in the wellbore. Shearing blind rams additionally close and seal against the pressure below. Casing shear rams are designed specifically to shear casing, and may not seal the well bore.
Source: API SPEC 16D, Specification for Control Systems for Drilling Well Control Equipment and Control Systems for Diverter Equipment, Upstream Segment, Second Edition, July 2004. Global Standards