Overview & First Impressions
Four versions of the same knife, all 2.99 inches of M390, all titanium, all 3.07 ounces, all 6.69 inches overall. The Firefly Ultra YD04 range only differs in finish, which makes it the cleanest way to decide how much you care about looks. The variants are RG with rose gold PVD, S, M with a mirror finish, and ST with a solid titanium blade. Same lock, same bearings, same geometry. The decision is entirely aesthetic plus a small price step.
Materials & Construction
Every version except the ST runs M390, a vanadium rich powder steel that trades a little toughness for excellent wear resistance. The ST goes to a solid titanium blade, which will never rust and is remarkably light, but titanium does not hold a fine edge the way steel does, so it is a collector piece rather than a workhorse. The handle is titanium across the board, and the swedge grind gives the whole family a slimmer profile than the numbers suggest.
Design & Details
The crossbar lock is shared, and it is the best part of the package. Ambidextrous, glove friendly and safe to close one handed, with ceramic bearings underneath for a smooth open. That lock is still rare on folding knives in this price bracket, which is exactly why the line gets recommended so often. The RG rose gold PVD is the flashiest option and it photographs far better than it sounds, more warm bronze than costume jewellery.
Real-World Use
In the hand all four feel identical, so this is a pure aesthetics purchase. I carried the RG for a fortnight and the PVD held up well, no scuffs on the flats, just a slight sheen along the bevel where it meets cardboard. The mirror M shows every fingerprint and every micro scratch, so if you use your knives rather than display them, the S or the RG is the smarter call. The ST belongs on a shelf and there is nothing wrong with that.
Ownership Notes
M390 at this hardness wants diamond or ceramic abrasives, and a strop will keep it going for months between real sharpenings. Keep the pivot clean; a drop of light oil every few months is enough. Do not oil a mirror finish, it just smears. If you own more than one version, store them apart, because titanium rubbing on titanium leaves marks that never come out.
Who Is This For?
Buy the S if you want a working knife that still looks premium. Buy the RG if you want personality. Buy the M if you appreciate a mirror polish and do not mind maintenance. Buy the ST if you collect titanium blades or want something that simply cannot rust. All four are EDC knives for people who want a compact modern folder with a lock that is easy to live with.
Final Verdict
The Firefly Ultra line is the easiest Trivisa family to recommend, because you cannot pick badly. The steel and the action are the same on every knife; the only variable is how much maintenance you want. Start with the S unless you already know you want shine. EdcMall stocks the range so you can compare finishes side by side before deciding.
