The technical specification: 1. The density≥1.80g/cm3 2. Water absorption rate≤0.15% 3. Bending strength≥400Mpa 4. Compression strength≥98Mpa 5. Withstand voltage along laminas at normal condition 5 min ≥25KV 6. Withstand voltage across laminas at transformer oil 90±2oC 5min ≥12MV/m Note: The diameter according to customer's order.