The TV Series features an injection-molded vinyl tapered design that can be used as a cap or a plug. Using an a-80 Shore durometer (hardness) vinyl, these caps resist tearing, cracking, splitting and shredding. Highly flexible, they enable snug fits even with smaller dimensions and irregular shapes. Easy installation and removal.:: a: 0.880, b: 0.950, C: 0.720, D: 0.790, E: 0.650, F: 1.16.