1) Materials: 7001-T6/T9, 7075-T9 alloy 2) High strength: 660Mpa 3) Light weight: 7001 or 7075 aluminum alloy is lighter than 6063 And 6061 4) Tightness tolerance: A) Inner diameter: ±0. 02mm B) Outer diameter: ±0. 02mm 5) Weight: ± 0. 5% 6) Straightened to 0. 15mm