Dr. Dolly 32K/20+2 sheets of primary school students’ calligraphy book for first grade writing book for kindergarten Tianzi grid calligraphy book excerpt notebook Chongqing primary school standard homework book 10 sets

**Specifications:**

**Brand:** deli

**Product Name:** Bullet Tip Gel Pen Refill

**Ink Quality:** High-quality ink with low resistance ballpoint for smooth writing

**Color Options:** Red, Gel Black, Dolli Blue, Oeli

**Tip Type:** Bullet tip with cap

**Quantity:** 20 refills per box, 0.5mm each, 3 colors available

**Ink Brand:** Mikuni, vibrant and long-lasting colors with good adhesion

**Ink Composition:** Scientifically formulated to prevent paper penetration

**Ballpoint:** Low-resistance ballpoint for smooth and easy writing

**Ballpoint Material:** Swiss-made Mikron tungsten carbide with reduced surface roughness (0.012Ra) and friction coefficient (0.2μ)

**Friction Coefficient Comparison:** Regular: 0.34u, deli: 0.2u

**Surface Roughness Testing:** Conducted in deli laboratories, slight variations may occur due to external conditions

**Friction Coefficient Standard:** Should be <0.35 according to international standard GB/T37853-2019

**Multi-Purpose:** Compatible with various retractable gel pens

**Gel Refill:** Black ink refill, No.6916, suitable for bullet tip pens

**Pen Body:** Transparent with soft rubber grip for ink visibility and prevention of ink drying

**Pen Cap:** Reusable pen tip cover

**Product Information:**

– Brand: deli

– Model: GEL Ink Refill No.6916

– Size: 130mm

– Writing Colors: Black/Red/Blue

– Line Width: 0.5mm Bullet Tip

– Packaging: 20 refills per box

– *Measurement Tolerance: ±1mm, please refer to actual product for accurate dimensions*