Piolt Hi-Tec-C Slim Knock 0.4mm Blue and Blue-Black

I ordered these pens from Ebay about 8 months ago, I wanted to try this version of the Hi-Tec-C pens, and found out it's got some advantages and some disadvantages.
to make it simple:

Advantages:
1. Suits right in my notepad.
2. Writes smoothly (just as it should).

Disadvantages:
1. A bit too small, my husband for example did not feel comfortable using it.
2. The ink barrel is significantly smaller than the regular Hi-Tec-C pen.

a Hi-Tec-C on the left,
next to the Slim-Knock Hi-Tec-C on the Right.

Here I took apart the Slim Knock on the bottom,
and above - the regular Hi-Tec-C.