This is a BLACKHAWK Lanyard known as the Coil, model 90TPL2BK.
This tactical pistol coil lanyard with single swivel gives an extra level of security" while still allowing full extension for tactical situations.
Features:
With swivel
Made with coiled wire and black rubber external laminate
Attaches to belt with loop or to weapon with gutted 550 cord
Allows full extension while shooting