Precision Pen Engineering
The idea of creating a pen jacket has been quietly growing within DeFF since 2020 — a small spark born from our desire to elevate everyday writing into something more meaningful. What began as a simple thought soon evolved into a long pursuit of form, material, and precision.
Over the course of three years, our design and engineering teams devoted themselves to continuous prototyping, testing, and refinement — exploring how metal and wood could coexist in perfect balance with a refill mechanism that adapts to thousands of pens worldwide.
This journey was not only about making a new product, but about redefining what a writing tool could be: a lasting companion that reflects the care, patience, and quiet determination behind its creation.
1. Material and Design
Each DeFF Refill Pen Jacket embodies the essence of Japanese craftsmanship in its purest form. The body is made from high-grade materials such as Aluminum, Titanium, or Natural wood, and meticulously shaped through CNC precision machining, polishing, and anodizing to achieve a flawless balance of strength and elegance.
From the gentle curvature of the body to the seamless junctions between each surface, every detail speaks of refined engineering and quiet beauty. Among them, the Stream Design Collection (Natural Wood Series) stands as a warm expression of this philosophy — where the natural grain of each wooden piece makes every pen truly one of a kind. Through such designs, DeFF reaffirms our belief that a writing tool should not only perform perfectly, but also reflect the individuality of its user.
2. Inner Construction
Beneath the sleek exterior lies a precisely engineered mechanism that allows compatibility with OVER 1000 types of ballpoint refills worldwide. By optimizing the internal diameter, depth, and locking structure, DeFF has created a flexible system that securely fits a wide range of refills without the need for modification.
It represents the fusion of mechanical precision and user-centric design — letting us keep the refill we love while elevating both writing comfort and aesthetic experience.
3. Everyday Usability
More than a writing instrument, DeFF's Refill Pen Jacket is a refined daily companion. Compact, durable, and effortlessly functional, it fits naturally into your pocket, notebook, or workspace.
Each stroke of the pen — whether cooled by Aluminum/Titanium or warmed by Wood — reminds us of the beauty of fine craftsmanship and thoughtful design. It embodies DeFF’s vision of creating tools meant to last, where even the simplest object carries intention, precision, and soul.
Pen Jacket Lineup
EVOLUTION
2023
1st Gen Pen Jacket
The first-generation Pen Jacket embodies DeFF’s original vision: transforming an ordinary pen into a refined, premium writing instrument. Crafted from Aluminum / Titanium, paired with a stainless-steel grip and collet, this model delivers a well-balanced structure that enhances stability and hand feel — resulting in a smoother, more solid writing experience than typical plastic-bodied pens.
2024
2nd Gen Pen Jacket
In second generation, DeFF introduced a new direction: a barrel made from natural wood, offering not only a sophisticated appearance but also a sense of individuality — as each wood grain is truly one of a kind.
The pen retains its compatibility with a wide range of standard ballpoint refills, using a collet mechanism that keeps the refill steady and minimizes wobble. Weight distribution and ergonomics are refined for better balance, ensuring stable and comfortable writing.
2025
3rd Gen Pen Jacket
The third-generation design incorporates the innovative “Magnalock” mechanism, using magnets on both the cap and the tail for secure and effortless attachment — a modern alternative to traditional clips or screw threads.
Inside, the collet system continues to support various standard refills without requiring length adjustments or additional components, preserving the flexibility and convenience that users appreciate.
2025
4th Gen Pen Jacket
The latest generation is designed for modern lifestyles, featuring an ultra-short form factor that is easy to carry and ideal for quick notes or on-the-go writing.
The 4th generation represents the evolution of DeFF — from elevating a simple pen into a premium tool, to refining it into a compact, minimalist everyday essential — all while maintaining the core values of quality, ergonomics, and refill versatility.
