An aluminum handle is machined or forged from aluminum alloy, usually anodized for color and corrosion resistance. It is light, rigid and inexpensive, and it is very common on mid-priced folders.
Aluminum gives a solid, rigid handle at roughly a third the density of steel. Set beside a stainless handle, it has a page of its own: Aluminum vs Stainless Steel. Anodizing adds a hard oxide layer that resists corrosion and takes color, and Type III hard anodizing is genuinely tough.
It is also cheap to machine, which is why it appears across so much of the market, from budget folders to premium ones.
It is cold. In freezing weather a bare aluminum handle draws heat out of your hand noticeably faster than G10 or Micarta.
It dents rather than chips. A hard knock leaves a permanent mark, and once the anodizing is breached the exposed aluminum will oxidize, though not in the destructive way steel rusts. Texturing or a rubber inlay solves the grip problem most designs otherwise have.
The term is not academic here. 173 of the products currently on our shelves describe this feature in their own manufacturer specifications, across 7 of the nine brands we stock. Examples in stock right now include Gerber Savvy Pivot Lock Gray, Case Marilla Linerlock Black, Gerber Fastball Linerlock Bronze.
Everything below is pulled live from the catalog, so what you see is what is actually in the Woodlawn warehouse today.