A cap for use in a neck of a laboratory vessel, such as a roller bottle, is disclosed. In embodiments, the cap is assembled from two parts, an annular skirted cap body and a cap insert. In embodiments the cap insert has integral connectors for attaching tubing, vents, filters, or the like. In embodiments, the cap insert fits into the annular skirted cap body through a rotatable fitting. In embodiments, when the cap is assembled, the top portion of the cap, having integral connectors, is rotatably fitted to the annular side wall of the cap.
