Capsule (12) to contain a substance (14,130) that needs to be contained in hermetic isolation, including the capsule: a first part of capsule (2) of flexible material to contain the substance (14), presenting the first part of capsule (2 ) a closed end (5), an opposite open end (6) and a predetermined length dimension defined between the ends (5, 6) thereof； a second capsule part (4) of flexible material having a closed end (7), an opposite open end (8) and a predetermined length dimension defined between the ends (7, 8) thereof, which is shorter that the length dimension of the first capsule part (2)； a cap (132) which is fixed to one of the first capsule part (2) and the second capsule part (4) so as to define an additional chamber (136) within which an additional substance (130) is contained； the closed end (7) of the second capsule part (4) being located inside the first capsule part (2) so that a region of the second capsule part (4) overlaps a region of the first part of capsule (2) so as to close the open end (6) of the first capsule part (2) and define a chamber (104) within which a substance (14) is contained, the capsule (12) being characterized because the open ends (6.8) of the first capsule part (2) and the second capsule part (4) are aligned flush with each other.Cápsula (12) para contener una sustancia (14,130) que precisa ser contenida en aislamiento hermético, incluyendo la cápsula: una primera parte de cápsula (2) de material flexible para contener la sustancia (14), presentando la primera parte de cápsula (2) un extremo cerrado (5), un extremo abierto opuesto (6) y una dimensión de longitud predeterminada definida entre los extremos (5, 6) de la misma； una segunda parte de cápsula (4) de material flexible que presenta un extremo cerrado (7), un extremo abierto opuesto (8) y una dimensión de longitud predeterminada definida entre los extremos (7, 8) de la misma, que es más corta que la dimensión de longitud de la primera parte de cápsula (2)； un ca
