Annular Bop must be used with hydraulic control system．It is usually with ram type BOP，but it can also be used independently. It can be used for following operations：
It can seal on almost any shape of size-Kelly，drill pipe, tool joints, drill collars, casing or wireline．
When there is no drilling tool in hole, it can completely shut off the hole．
With an accumulator，forced tripping with 8°/35°welded tool joints is allowed.
for after-sale service