The feature: 1.Block the tap hole,need the stemming with good filling ability and Sinterability. 2.Stable Tapping ,required stemming easy open corrosion resistance,abrasion resistance 3.Easy to operation ,easy drilling.. 4.Moderate plasticity, easy to operation and forming the taphole balling 5.Protect the cylinder,need stemming quickly heating no crack,and high adhesive strength for fresh and old stemming. 6.Good volume stability,under high temperature have small change on the volume,no leakage of molten iron ,because of volume range.