Aluminum is significantly lighter than steel and is therefore fat more popular in the outdoor and climbing industries where weight is a major factor.
Locking Gate come with a separate mechanism or sleeve that ensures the carabiner does not accidentally open.
Screw Locking gate is the most common. A sleeve must manually be loosened to unlock or tightened.
Key nose carabiner does not have a notch to snag onto anything. Making clipping/unclipping simple.
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.