The disclosure relates to a slider and a reclosable zipper, particularly a zipper with first and second profiles for watertight vessels, packages or similar devices. The slider is generally C-shaped with an upper arm, a lower arm, and a support wall in between. The support wall includes a groove which captures a rail formed on the first profile so that the slider can slidably move along the rail, riding the first profile. The lower arm includes separator blades which separate the first and second profiles when the slider is moved in the opening direction so as to urge the second profile between the upper and lower arms. When the slider is moved in the closing direction, the second profile travels between the upper and lower arms and is urged into engagement with the first profile by the upper arm. At the final closing position, the slider is stabilized or parked within a cut-out portion of the second profile.