If you enjoy the forum please consider supporting it by signing up for a NES Membership The benefits pay for the membership many times over.
What Firestorm showed is a military style shoulder holster
What firestorm showed is a military style holster. Zappa is correct but the piece that anchors the strap to your belt may be missing.
The strap goes behind your neck, down the front of your right shoulder and snaps over your belt: