**Product Specifications:**
**Brand:** BAOKE
**Model:** S21
**Pen Type:** Calligraphy Pen
**Nib:** Special Fiber Nib
**Ink Absorption:** Efficient
**Ink Refill Method:** Twist open the cap, insert the cap into the pen end, unscrew the rear plug, fill with special ink, and tighten the rear plug.
**Size:** Pen - 144*12mm, Ink - 74*13mm
**Suitable for:** Signing, reviewing, calligraphy practice, etc.
**Features:** Even ink distribution, quick-drying, waterproof, moderate softness and hardness, comfortable grip, classic pen body, durable, fixed pen clip for easy carrying, selected pen tip for uniform ink output.
**Ink Type:** BAOKE Fine Ink +1521
**Ink Color:** Deep Black
**Specialty:** Calligraphy-specific ink refill
**Compliance:** BAOKE Ling, Qualified 2881
**Usage:** Suitable for calligraphy, regular writing, and artistic creation.
(Note: The information provided is based on the input content.)
