Active combat entails an unconditional risk of damage to equipment. Slings, fastexes and other details can be damaged and the nearest workshop is very far away. At such a moment, a repair kit will come in handy. 

This kit include everything what do you need - two fastex for different type of equipment (vest and sling), plus small piece of fabric and blue tape - izolenta for repairing metal parts or slings/vests. Come as set.