Features

１、This packer is a packer of a balanced type, which means that the pressure of upside and downside of the packer is the same. It is impossible to unseal because of the overpressure of the upside. 

２、It has the functions to prevent from midway sealing and to self-centralize, what prevent the influence of pipe column off-center moving from casing on the sealing effect of the packer.