A connector for coupling to a base of medical device equipped with a circular hub having an annular recess. The connector includes a cap having a top surface, a bottom surface, a circumferential region defining a bottom plane and a periphery, and at least two arms substantially parallel to the bottom plane. Each arm spans at least two portions within the circumferential region to releasably engage the annular recess. At least one deflection member that is accessible from the top surface is positioned to deflect the arms. Pressing the connector onto the circular hub engages the arms with the annular recess so the connector can rotate completely about the circular hub. Pressing at least one deflection member to reversibly deflect at least one arm between its two portions of the circumferential region towards the periphery disengages the arm from the annular recess to decouple the connector.