AustriAlpin
Sym Oval Clawlock Screwgate v1

An old school steel oval which has been in production for decades. This one was left in a non-climate controlled building for a couple years in the bottom of a box of assorted defunct equipment - it's seen better days.

Notable here are two features: The claw lock gate, and a nose-stopped locking sleeve.

The gate and nose mate using a "clawlock" arrangement where a surface on the gate overlaps with another surface on the nose, rather than the more commonly found pin & hook or keylock styles. I have seen this style present on many steel carabiners, but no (rated) aluminum carabiners. My guess is that the soft aluminum would require a much larger surface/gate/nose to resist deformation.

The locking sleeve will rotate until fully jammed against the curvature of the nose of the carabiner, and can be difficult to loosen - especially after load. Users of such carabiners (such as me on my first ropes course job) were instructed to rotate the sleeve until it stopped, then back it off a quarter-turn. Modern screwlock carabiners have a stop integrated into the gate - usually a metal snap-ring hidden behind the locking sleeve. Gate-stopped screwlockers will still permit minor movement of the gate when locked. Nose stopped carabiners will have no movement at all with the locking sleeve jammed against the nose.