A fluid transfer system includes Luer male and female connectors. The male connector has a main body with a longitudinal internal opening and an internal threading the female connector has a main body containing an internal channel for the passage of fluids, a collar that surrounds at least a portion of an end of the main body, and external threading on the portion that is surrounded by the collar. The corresponding threadings are configured to engage and ensure a secure fit between the male and female connectors. An external surface of the male connector at the end where the threading is located forms a conical male portion, the internal surface of the collar of the female connector forms a conical female connecting surface, and the conical male portion is configured to fit against the conical female connecting surface and onto the collar when the male and female connectors are fitted together.
