uni-ball one F 0.38 Keshizumi

Step into the realm of ultimate stealth-chic with the uni-ball one F 0.38 Black, carrying the exact product code UMNSF38F.24. Famously known in Japan as the "Keshizumi" (消炭 - Charcoal Black / Faded Black) edition, its design is inspired by the quiet, comforting image of charcoal embers cooling after a long fire. To achieve its beautifully ink-dark aesthetic, this is the only model in the regular lineup featuring a matte black coated wire clip instead of the standard polished silver metal, creating a flawlessly uniform, tactical look.

The uni-ball one F is an ergonomic upgrade from the everyday plastic gel pen. It sheds the traditional rubber sleeve in favor of a seamless, smooth matte body and incorporates a heavy-metal internal stabilizer. By biasing the weight forward toward the paper, it grounds your writing experience for smooth, wiggle-free performance.

Key Features

• Stealthy "Keshizumi" Faded Black Finish: A deep, charcoal-black matte body paired seamlessly with a matching matte black metal wire clip. It offers a sleek, executive, or tactical look that anchors any minimalist workspace.
• Low Center of Gravity (Stabilizer Mechanism): Engineered with a precision-machined metal nose cone tucked inside the tip. This forward-weighting design allows the pen to write smoothly under its own weight, dramatically reducing hand fatigue over long drafting sessions.
• Ultra-Fine 0.38mm Black Ink: Features a rock-solid, wiggle-free conical tip that makes it an absolute favorite for tight planner grids, margins, or intricate sketch linework.
• Guinness Record-Breaking BEADS-PACK Ink: Utilizes unique pigment-encapsulation technology where the ink sits crisply on top of the paper fibers rather than bleeding or soaking into them, creating exceptionally dark, high-contrast lines.
• Rapid-Drying & Smudge-Free: The fast-absorbing liquid carrier evaporates almost instantly upon hitting the page, locking the intense pigment onto the paper surface. This ensures your journals, letters, and notes stay clean—even for left-handed writers.
• Oversized Open Wire Clip: Features uni-ball's iconic spring-loaded wire pocket clip that opens incredibly wide, clamping securely onto thick cardboard folders, leather notebook covers, or heavy-duty planners.

Specifications at a Glance

• Barrel Color: Keshizumi (Faded Black / Charcoal / 消炭)
• Ink Color: Carbon Black
• Tip Size: 0.38 mm (Ultra-Fine Precision)
• Model Code: UMNSF38F.24
• Weight: 14.3 g (Perfectly balanced forward weight)
• Dimensions: 139.2 × 11.1 mm
• Refill Type: Fully refillable with standard UMR-38S / UMR-05S gel cartridges.