Material: UL qualified NYLON6 (black),
Fire rating: 94V-2, not aging, high insulation
Uses: 1. Expand the contact surface, reduce the tightening force on the fastener stress concentration, to prevent damage to the fasteners.
        2. Do not scratch the fasteners when tightening the nuts.
        3. The mats and spring mats also prevent the nut from loosening.
Packing: 1000PCS