Upgrade list
1) Differentiated comb thickness at front section (front side thicker then rear ones)
2) 5 turns of air/ink path (Most ebonite feeds 1 turn), stability increased.
3) micro slitting across the front part added, to inprove function and stability
4) tail thickness significantly increased to improve durability
5) feed overall thickness increased
*below is the lastest version: 3G V5.0, not V4.0 (as of 10/05/2019)
