The Tajima AC-700B Rock Hard Aluminist With Auto Blade Lock is a heavy-duty snap-off utility knife built for repeated cutting and trimming work on the jobsite. This is a utility knife designed for general cutting, scoring, and material trimming. Model number AC-700B. With a die-cast aluminum body, 25 mm blade format, and auto blade lock, it is aimed at contractors and serious users who want a sturdier knife than the throwaway options riding around in most buckets.

The big story here is the combination of a wide 1 inch blade and a rigid aluminum handle. That wider blade gives you more support during heavier cuts, which matters when you are working through dense material or making long scoring passes where blade flex can ruin the cut. The auto blade lock keeps blade adjustment quick, so you can set exposure for shallow scoring or extend further for deeper trimming without slowing down.

Tajima builds this knife around a die-cast aluminum handle instead of a lighter plastic body, and that changes how the tool feels in use. You get a more planted, solid hand feel and better durability if the knife is used hard every day. The ergonomic handle shape also helps when you are making repeated cuts through sheet goods, flooring, insulation, packaging, or jobsite materials that would quickly show the weak points in a bargain knife.

This model also keeps the practical details in mind. The knife includes in-handle blade storage, so replacement segments or spare blades are close at hand instead of buried in a toolbox. It ships with three ROCK HARD blades, giving you a ready-to-work setup right out of the package. The blade material is listed as SK-120 steel, which is a meaningful spec because blade steel quality directly affects edge life, snap consistency, and how cleanly the knife keeps cutting as the workday goes on.

For real-world jobsite use, the retractable design and keyless blade change matter just as much as the body material. A retractable utility knife is easier to carry safely in a pouch or pocket, and keyless blade changes make maintenance faster when you need to swap in a fresh edge. The lockable design also gives you more confidence when you are bearing down on tougher cuts and need the blade to stay put.

Compatibility is straightforward. The AC-700B uses 1" (25 mm) snap-off utility blades, and Tajima specifically calls out ROCK HARD replacement blades LCB-65. That is useful if you already run Tajima knives and want to stay on the same blade format, or if you are setting up a crew and want one replacement blade type to stock.

Who should buy it? This is a good fit for contractors, remodelers, flooring installers, drywall crews, general carpenters, and serious DIY users who are tired of flexy utility knives. If you cut often enough to care about handle strength, blade stability, and quick access to spare blades, this model makes sense. If you only open a box once a month, it is more knife than you need. For daily carry and regular cutting work, it is the kind of tool that earns its spot fast.

Why the Tajima AC-700B Rock Hard Aluminist With Auto Blade Lock Earns Its Keep

This is the kind of utility knife you buy once because you are done messing with flimsy bodies and sloppy blade action.

• Who it's for: Pros and heavy-use DIYers who cut often enough to notice handle flex, poor blade support, and cheap lock mechanisms.
• Why it stands out: The die-cast aluminum body, wide 1 inch blade format, and in-handle blade storage make it feel like a real work knife, not a disposable backup.
• Worth knowing: This is built around 1 inch snap-off blades, so make sure that is the blade format you want to keep stocked on the truck.

• What blade size does this knife use? It uses 1" (25 mm) snap-off utility blades.
• Does it have blade storage in the handle? Yes. Tajima lists in-handle blade storage as a core feature.
• What type of lock does it use? This model uses an auto blade lock mechanism.
• Are replacement blades available? Yes. Tajima calls out ROCK HARD replacement blades LCB-65 for this knife.