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Description
The Apex of Japanese Metallurgical Mastery: ZDP-189 Steel
At the heart of the Rockstead RYO-H is a blade forged from Hitachi ZDP-189, an elite powder metallurgy stainless steel renowned for its jaw-dropping carbon and chromium content. Hardened to an astonishing 67 HRC, this steel provides a surgical cutting edge that defies standard wear patterns, outlasting conventional premium super-steels (like M390 or S90V) by a massive margin.
To optimize this high-hardness core for real-world reliability, Rockstead utilizes a clad construction, wrapping the ZDP-189 core in tough, flexible stainless steel. This lamination provides crucial lateral strength and structural flexibility, mitigating brittleness while maintaining an edge that stays razor-sharp for years of light-to-medium use.
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Blade Material: ZDP-189 Powder Stainless Steel (Clad in Soft Stainless Steel)
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Hardness: ~67 HRC (Unmatched Edge Retention)
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Blade Grind: Honzukuri (Convex Zero-Grind) Mirror Polished
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Handle: 3D-Machined Solid Titanium (Anodized Blue Finish)
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Unique Feature: Patented Concealed/Retractable Clip System
ZDP189 Blade Introduction
ZDP-189 is a high-carbon, high-chromium powder metallurgy steel renowned for its extreme hardness, often exceeding 64 HRC, which delivers peerless edge retention and aggressive cutting performance. This performance comes at a cost; its massive carbide volume makes the steel notoriously difficult to sharpen and increases brittleness, posing a risk of chipping under heavy lateral impact. Furthermore, while technically stainless, its high carbon content necessitates diligent maintenance to prevent oxidation, making it a specialized choice for precision cutting tasks rather than rough, heavy-duty utility.
RYO H-ZDP (BL)
| Full length | 196mm |
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| Blade length | 80mm |
| Total weight | 124g |
| Blade thickness | 3.2mm |
| Blade material | ZDP189 |
| Blade hardness | Around 67 HRc |
| Handle material | titanium |
| Handle coloring | blue |
It is very easy to use and cuts well. This handle material is titanium and blade material is ZDP189.
The greatest feature of this knife which is movable clip system that called "Concealed clip system". We have originally produced the concealed clip system to eliminates the uncomfortable feeling of the "clip feel" when gripped the handle. However, it turns out that a part of the mechanism of this "concealed clip system" conflicts with US patent Nos. 8,112,894 and 8,783,141.
We have bee licenced to use the US patents after negotiations with Mr. Joseph Caswell, the US patent owner.
Why Invest in a Rockstead Knife?
Rockstead knives are widely recognized as "factory custom" knives—combining the micron-level precision of high-specification CNC machining with traditional artisan hand-craftsmanship. Every single knife is serialized and comes with access to Rockstead's legendary sharpness warranty, allowing you to send the knife back to Japan for factory restoration and sharpening.
For the elite EDC collector who demands structural perfection, historical Japanese lineage, and boundary-pushing mechanical innovation, the Rockstead RYO H (BL) is not just a tool—it is an unparalleled investment piece.
Rockstead RYO-H FAQ
1. What makes the Rockstead RYO H (ZDP) pocket clip unique?
The Rockstead RYO H features a revolutionary, patented concealed pocket clip system. When carrying the knife, you can pivot the clip out to secure it to your pocket. However, when you grip the handle to use the knife, natural palm pressure forces the spring-loaded clip to retract completely flush inside the 3D titanium scales, eliminating uncomfortable grip "hot spots."
2. How long does the ZDP-189 blade steel on the Rockstead RYO stay sharp?
Thanks to Hitachi's elite ZDP-189 powder stainless steel hardened to an astonishing 67 HRC, the RYO H offers unmatched edge retention. It can outlast conventional premium super-steels (like M390 or S90V) by a massive margin. Under normal, non-destructive EDC use, a Rockstead blade can easily maintain its razor-sharp edge for years before needing factory maintenance.
3. Can I sharpen the Rockstead RYO H Honzukuri convex edge at home?
It is highly recommended to send the knife back to Rockstead in Japan for sharpening. The RYO H utilizes a specialized Honzukuri (mirror-polished, zero-bevel convex) grind. Traditional sharpening stones or angled systems can ruin the flawless mirror finish and alter the complex geometry of the edge. Every authentic, registered Rockstead knife comes with access to their legendary factory sharpening service.
Titanium coloring reacts to oil, so even if the color of the handle changes, there is no problem on the product. When wiping it with alcohol or neutral detergent attached to the tissue, it becomes the original bright color.
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Delivery and Shipping
In-stock orders will be shipped in 48 hours except weekend and holidays.
Pre-orders pls subject to the indicated Pre-order shipping dates.
From China warehouse: Estimated delivery in 15–21 business days