An apparatus, comprising: an expandable sheath comprising: a cylindrical or substantially cylindrical expandable frame having a proximal opening, a distal opening, an inner surface, and an outer surface; and a material covering the outer surface of the expandable frame and a portion of the inner surface of the expandable frame, and forming a step feature within the distal opening, the step feature having a first surface that abuts the inner surface of the expandable frame and that is oriented at a first angle relative to the inner surface of the expandable frame; a dilator comprising: a cylindrical or substantially cylindrical body ; a tapered tip ; and an interlock between the body and the tapered tip having a first cylindrical section with a first outer diameter, a second cylindrical section with a second outer diameter that is less than the first diameter, and a catch surface that abuts the first cylindrical section and that is oriented at a second angle relative to the first cylindrical section; and wherein the dilator is configured to be inserted into the expandable sheath through the proximal opening of the expandable frame; and wherein the catch surface is configured to engage the first surface to resist the body of the dilator from passing out of the expandable frame through the distal opening. an expandable sheath comprising: a cylindrical or substantially cylindrical expandable frame having a proximal opening, a distal opening, an inner surface, and an outer surface; and a material covering the outer surface of the expandable frame and a portion of the inner surface of the expandable frame, and forming a step feature within the distal opening, the step feature having a first surface that abuts the inner surface of the expandable frame and that is oriented at a first angle relative to the inner surface of the expandable frame; a cylindrical or substantially cylindrical expandable frame having a proximal opening, a distal opening, an inner surface, and an outer surface; and a material covering the outer surface of the expandable frame and a portion of the inner surface of the expandable frame, and forming a step feature within the distal opening, the step feature having a first surface that abuts the inner surface of the expandable frame and that is oriented at a first angle relative to the inner surface of the expandable frame; a dilator comprising: a cylindrical or substantially cylindrical body ; a tapered tip ; and an interlock between the body and the tapered tip having a first cylindrical section with a first outer diameter, a second cylindrical section with a second outer diameter that is less than the first diameter, and a catch surface that abuts the first cylindrical section and that is oriented at a second angle relative to the first cylindrical section; and a cylindrical or substantially cylindrical body ; a tapered tip ; and an interlock between the body and the tapered tip having a first cylindrical section with a first outer diameter, a second cylindrical section with a second outer diameter that is less than the first diameter, and a catch surface that abuts the first cylindrical section and that is oriented at a second angle relative to the first cylindrical section; and wherein the dilator is configured to be inserted into the expandable sheath through the proximal opening of the expandable frame; and wherein the catch surface is configured to engage the first surface to resist the body of the dilator from passing out of the expandable frame through the distal opening. <EOS>