This Knife Should Be Illegal In California. Here’s Why It’s Not

The exceptional collaborative design takes three times as long as normal to produce.

Terrain 365 x Prometheus Design Werx CAS OTF knives laying on green blue and orange ropes

Published December 11, 2024

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California has some of the strictest knife laws in the country. Many styles of EDC knives, including OTFs (short for out-the-front), are banned outright.

Some brands, however, have found legal loopholes, skirting the regulations through clever design to produce completely California-legal knives. The Terrain 365 x Prometheus Design Werx CAS OTF is one such knife, and it is exceptional from tip to tail.

Terrain 365 x Prometheus Design Werx CAS OTF knives laying on a swim fin atop a topographical map — The CAS OTF has one of its class’s cleanest, most minimal designs.

Legalize it

As mentioned, California Penal Code 21510 makes most OTF knives illegal. Possessing, carrying, or selling them can result in up to $1,000 in fines and six months in jail.

So, how did PDW and Terrain 365 make the CAS OTF legal to sell, own, and carry? They kept its size below the legal limits.

Short for California Special Out the Front, the CAS OTF’s rustproof Terravantium blade measures up at just 1.925 inches, less than a tenth of an inch smaller than California’s 2.0-inch limit.

As such, they’re well within their rights to sell it in the state. That also means it’s well within your rights to own and carry it like any other EDC knife if you’re a California resident.

Editor’s Note: Rules and restrictions vary from region to region, so please check your local carry laws before buying.

side of Terrain 365 x Prometheus Design Werx CAS OTF knife on blue-pink gradient background — The jimping on the knife’s handle gives it some much-needed grip and increases the available leverage.

An exercise in precision

The CAS OTF is made from pretty spectacular materials, including the Terravantium blade and a handle built from 6AL-4V titanium and T6061 aluminum. There’s even a luminous Hyperglow dot on the deployment slider for easier low-light operation.

But the most impressive part of the knife’s construction is its machining. The unusual contours of the handle require three times as long as usual on the CNC.

Furthermore, the presentation side of the knife — the side without the pocket clip — is completely free of screws and other clutter. The result is a super-clean, beautiful minimalist aesthetic, unusual for a knife of this style.

Terrain 365 x Prometheus Design Werx CAS OTF knife handle on blue-pink gradient background — The CAS OTF’s overall length is just over three inches, making it as compact as possible.

Pricing and availability

While the CAS OTF is listed on both Prometheus Design Werx and Terrain 365’s sites, it’s only currently in stock in three of five colors via PDW.

The three in-stock colorways — Black, Dark Gray and Tyrian (AKA purple) — are listed at $195 and ready to ship immediately. But if the other colors are any indication, they probably won’t stay in stock for long.