PRIMO-2-Outer Dimension: 9.5" x 5.25" This round-top, ladder-hook carabiner is ideal for firefighters, rescue work & rigging. It has an auto-locking gate with an extra generous gate opening so it easily fits over ladder rungs. It is made of high density alloy steel for extra strength. Auto-locking decreases the possiblity the user will forget to lock the gateand prevents the gate from unlocking from vibrations while working.