PBI technology and DuPont Kevlar® made Gemini™ XT the number one selling PBI/Kevlar outer she! The thermal resistance of PBI and Dupont™ Kevlar® spun yarns is reinforced with a high-strength filament grid. Brochure Where To Buy WHY CHOOSE PBI XT? PBI XT (formerly known as Gemini XT) features a patented high-tech grid of composite filament and spun yarns that provides strength, reduces abrasion, and eliminates puckering. Superior abrasion resistance. Excellent thermal stability – strong and flexible before and after thermal exposure.