Diesel exhaust after-treatment system is the combination of DOC, DPF, SCR, ASC and POC. These catalytic units usually have quite larger diameter than TWC and GPF, and run in relative low temperature range. In this case, classical intumescent mat KY100 could not be used as it could not work well below 400deg.C. Micro-intumescent mat KY800 and its high-performance version KY860 are the best solutions in most cases. When the relative expansion of metal/ceramic gap is large, ultra-mirco-intumescent mat KY860 and non-intumescent mat CNE are prefered. When the gap is extremly large, PNE is better choice.