Exothermic Pulsefire LRT/UBF Sling Black. Specifications for Exothermic Pulsefire LRT/UBF Sling: Manufacturer: Exothermic Color: Black Features of Exothermic Pulsefire LRT/UBF Sling Adjustable length nylon sling for the LRT and UBF. Package Contents: Exothermic Pulsefire LRT/UBF Sling Exothermic PF-SLING: Pulsefire LRT/UBF Sling Black