A clip member for sealing an opening in a sheet material includes a body which is fluid tight in an axial direction, at least one flange portion adapted to engage a surface of the sheet material, at least one resiliently deformable arm attached to the body and radially bendable relative to the body for facilitating introduction of the body into the opening and locking of the body in the opening, and a deformable film surrounding the arm. The film is tied on both the body and the flange portion to seal the opening and deformed concurrently with the deformation or bending of the arm. A locking portion is provided on the arm to engage an edge of the opening when the body is fit into the opening with a snapping action of the arm.