This is the suspension buckle for the lifting hook for a very comfortable belt of 6 cm wide. (Circumference 130 cm, width 6 cm, adjustable in circumference)

It is available in the left and right version.

The pick-up hook hangs securely and always quickly on this buckle when the hook is needed. For retrieval it is handy that the collectors on the left and right carry one. 
Related. Empty 2 collectors at once if they are not completely full.