PPI gaw, inch langai hta hka htung ni a jahpan hpe tsun ai, sponge langai mi hta hka htung ni a density hpe shadawn na matu unit langai mi re.
40ppi silicone sponge gaw grau kaba ai pore size (npu na pore density), nbung n-gun grau law ai (nbung n-gun 30% kaw nna 50%) nga ai, san seng na matu loi ai. Nbung hpe grai law hkra bang ra ai (sh) chyahkring hkring san seng ai lam ni ra ai masa ni a matu htuk manu ai, ga shadawn, nbung hpe hka ja ai ladat ni.
60ppi sponge gaw, shi a n-gun ja ai pores ni a majaw (pre density 50% jat wa ai) a majaw, nsen hpe n-gun shayawm ai lam (8-12dB hpe shayawm kau ai) hte nbung n-gun shayawm ai lam (thermal resistance 20%-35%), acoustic engineering (sh) katsi ai hpe n-gun shayawm ai lam ni a matu htuk manu ai.