upgraded from v1.0:
1) design easier to urushi coat
2) end portions rounded to facilitate production
3) cleaner angle cut
4) grip shared with symmetry v9.2
5) grip front part more rounded (*vintage/aurora style grip design is prone to scratches when opening and closing cap, a unfavorable design for urushi coating)
(below grip is designed to reduce scratching when opening and closing cap)
6) grip ,at the end of the thread, stronger design
