Recently funded on Kickstarter, the Mako Rex 121 uses steel that approaches the limits of the Rockwell hardness scale.
Meet the Mako EDC, a super-steel knife meant for everyday carry. Knifemaker Gary Creely launched the model successfully on Kickstarter.
But it caught our eye because he used one of the most exotic steels on the market: CPM REX 121.
Super Steel: CPM REX 121
The Mako EDC is a 6.9-inch fixed-blade knife. It has a fairly large, nontraditional handle made with black G-10 scales. But enthusiasts will drool for its blade.
There, you find wildly hard Crucible CPM REX 121, a steel that Creely claims to harden to 68 on the HRc scale. For reference, the scale tops out at 70.

What does that mean for knife users? Basically, this knife will hold an edge longer than almost every other knife on the market – other than maybe a handful of blades made with Maximet and a few other super steels.
But it does come with drawbacks.
Mako EDC
REX 121 Steel: Hardness vs. Toughness
“A very pedestrian definition of toughness would be a steel’s ability to bend without breaking, or chipping as the case may be in knives. Typically, big choppers are made out of steels that have great toughness, a modern steel that exemplifies this would be CPM 3V. On the toughness chart, REX 121 would be at the bottom. This steel is also not a stainless steel, so if not cared for properly it will rust. REX 121 is a great chance to see how far steel technology has come in the specific area of edge retention.”