The Pyrite-Light in its dark-green state — pick it up and body heat drags it toward pale green.

A budget everyday-carry flipper with a party trick: its fiberglass-nylon handle is thermochromic, fading from dark green to light green as it warms in your hand and drifting back as it cools. The trick would be a throwaway if the knife under it weren’t a genuinely well-specced pocket knife for the money.

The color change is the reason to look twice. CJRB blends thermochromic particles into the FRN (fiber-glass reinforced nylon) handle, so warmth — from your palm, a pocket, a summer afternoon — shifts it from dark to light green, then lets it settle back as it cools. It is the ’90s Hypercolor T-shirt idea applied to a tool you actually keep, and unlike a printed coating it can’t wear off because the effect is in the material itself.

Underneath the novelty is a knife that would be worth its price plain. The blade is a 3.34-inch (85mm) Wharncliffe in AR-RPM9 — CJRB’s own powder steel, run to HRC 59–61 — ground flat from 2.5mm stock and finished with a stonewash that hides scratches. It rides on a ceramic ball-bearing pivot, flips open on a thumb stud, and locks up on a button lock, so one thumb both deploys and closes it. Closed it is 4.25 inches and 70 grams (2.47 oz), with a steel pocket clip: squarely pocketable, not a chore to carry.

What earns its place is the ratio. At $39.99 (from a $53.32 list), you are getting a button lock, a competent powder steel, and bearing action — a spec sheet that reads like a knife twice the price — with a genuinely fun material as the hook rather than the whole pitch. AR-RPM9 is a budget-tier steel, not a super-steel, so edge retention is good-not-heirloom and you’ll strop it more often than an S30V blade; the Wharncliffe’s straight edge is a clean slicer but skips the belly some prefer for general work. Those are the honest tradeoffs of a $40 knife. The thermochromic handle is the thing you’ll show people — but the knife is the thing you’ll keep carrying after the novelty cools.