Drop-in check valve is an internal prevener. When blowout is going to happen, the Kelly should be removed immediately and the check pressure valve assembly should be put into the water hole and then pumped downward to the required place. Thus the blowout can be prevented. The valve body connect on the drilling stem. Drop-in check valve is ball and seat of heavy duty, if only drop in the valve core at the mouth of the well, it turn into the valve body.