REI
Gold D Locking Carabiner (stepped nose)

In 1981, REI bought the Mountain Safety Research (MSR), which produced whitelabel carabiners for REI, as well as carabiners under their own name. Cascade Designs (Platypus, Thermarest, etc) bought MSR from REI in 2001.

MSR first advertised I-beam carabiners in 1993, touting the investment in time and money to develop the new line, and included a few features which were used in REI carabiners as well:

• rivet flats - the domed rivets sit flush and are less likely to snag on gear (typically the fibers of webbing)
• gate shield - an angled cut in the gate leaves (slightly) more material on the back side. Compare to a Black Diamond of that era.
• individual serial numbers
• 3σ Testing
• locking indicator - on the screwlock model

These innovations came at a time when the industry was on the cusp of adopting keylock (and other snagless nose) designs, hot-forging, and the wiregate. 3σ Testing (or similar) and larger gate shielding have become industry norms, as well as individualized serial numbers and locking indicators for some brands or user disciplines.

The "GO ON GREEN" locking indicator is obscured by the heptagonal (interesting choice!) locking sleeve when unlocked. As the carabiner is unlocked, the green becomes obsured 6/7ths turns before the gate actually unlocks (under no load). This style of positive-locking indicator clearly hasn't persisted with modern day screwlock carabiners, although some designs of twist locks with buttons use a green button for a Green-is-Go indicator.

This example has a stepped nose for the locking sleeve relief, in contrast with the similar angled nose model. The "GO ON GREEN" marking has been double stamped (bounced perhaps).