Knifeclub's Four-Inch Friday Shows the Big Folder Is Back
A thread titled simply 'Four-inch folder Friday?' ran through r/knifeclub on 23 October, and the timing is not a coincidence. The four-inch blade class is quietly rebuilding itself after a decade in which most manufacturers treated 3.5 inches as a hard ceiling.
The current generation of big folders is different from the ones that earned the class its reputation for being pocket bricks. WE's Sine Wave carries a 3.98-inch M390 drop point at 0.16-inch stock in a 4.96-ounce titanium frame. Kansept's Navaja runs 3.61 inches of CPM S35VN on a curved handle. Vosteed's Porcupine TiSlim goes the other way, with a 3.04-inch S90V blade in a frame only 0.315 inch thick. Thin stock and better steel — and in the TiSlim's case, thin handles — are what make a four-inch blade carryable now. For context on the weight question: the lightest four-inch folder in this week's coverage is the Vosteed Porcupine TiSlim, and its 3.04-inch blade keeps it out of the class entirely. The knives that actually compete at four inches are all between 4.3 and 5 ounces, which is the same weight as a loaded small frame lock plus a phone. That is the trade nobody has solved.
The trade-off people in that thread keep running into is legal, not mechanical. A four-inch blade closes a lot of doors: many US cities and several states draw limits at three inches, and the knife that feels best in the hand is often the one you cannot legally carry to work. That is the reason 3.25 to 3.5 inches became the default in the first place, and it has not changed.
The practical case for the class is reach. Four inches of edge folds through a whole pizza box in one pass and gives you enough blade to cut rope on a boat or break down a week of cardboard without the sawing that a 2.95-inch folder requires. The cost is pocket presence and weight, and no design has managed to eliminate either; the TiSlim attacks thickness, the Sine Wave accepts 4.96 ounces.
If you have been thinking about a bigger carry knife, the current generation is the best it has ever been. If you have a three-inch limit where you live, this is a class to admire from a distance.