Aluminum: is significantly lighter than steel and is therefore far more popular in the outdoor and climbing industries where weight is a major factor.
Non-Locking: Gates are for general use and are important when clipping quickly. All non-locking carabiners are spring-loaded to ensure immediate gate closure upon release.
Wire Gate: the most common gate used. Tends to be a bit stronger than bent gate carabiners.
Modified “D” shape: This shape helps to push the load to the back of the “spine”. Allows weight to be carried primarily by the spine and less by the gate—making for a stronger and lighter use.