A system for closed transfer of fluids comprising: a vial adapter comprising: a body having a first end and a second end; a vial connection extending from the second end of the body, the vial connection configured to secure the body to a vial; a vial spike extending from the second end of the body, the vial spike defining a passageway; and a collet connection extending from the first end of the body; and a syringe adapter comprising: a housing having a first end and a second end; a membrane housing positioned within the housing, the membrane housing moveable between a first position and a second position, the membrane housing including at least one membrane (32, 34); a cannula positioned within the housing, the cannula having a first end and a second end, the second end of the cannula positioned within the membrane housing when the membrane housing is in the first position and positioned outside of the membrane housing when the membrane housing is in the second position; and a syringe connection extending from the first end of the housing, the syringe connection configured to be secured to a syringe barrel, characterized in that: the collet connection is moveable between a first position where the collet connection is configured to receive the membrane housing and a second position where the collet connection is configured to be secured to the membrane housing, and the collet connection comprises a collet body and first and second arms (72, 74) extending from the collet body away from the first end of the body of the vial adapter, the first and second arms (72, 74) defining a space configured to receive the membrane housing. a vial adapter comprising: a body having a first end and a second end; a vial connection extending from the second end of the body, the vial connection configured to secure the body to a vial; a vial spike extending from the second end of the body, the vial spike defining a passageway; and a collet connection extending from the first end of the body; and a body having a first end and a second end; a vial connection extending from the second end of the body, the vial connection configured to secure the body to a vial; a vial spike extending from the second end of the body, the vial spike defining a passageway; and a collet connection extending from the first end of the body; and a syringe adapter comprising: a housing having a first end and a second end; a membrane housing positioned within the housing, the membrane housing moveable between a first position and a second position, the membrane housing including at least one membrane (32, 34); a cannula positioned within the housing, the cannula having a first end and a second end, the second end of the cannula positioned within the membrane housing when the membrane housing is in the first position and positioned outside of the membrane housing when the membrane housing is in the second position; and a syringe connection extending from the first end of the housing, the syringe connection configured to be secured to a syringe barrel, characterized in that: the collet connection is moveable between a first position where the collet connection is configured to receive the membrane housing and a second position where the collet connection is configured to be secured to the membrane housing, and the collet connection comprises a collet body and first and second arms (72, 74) extending from the collet body away from the first end of the body of the vial adapter, the first and second arms (72, 74) defining a space configured to receive the membrane housing. a housing having a first end and a second end; a membrane housing positioned within the housing, the membrane housing moveable between a first position and a second position, the membrane housing including at least one membrane (32, 34); a cannula positioned within the housing, the cannula having a first end and a second end, the second end of the cannula positioned within the membrane housing when the membrane housing is in the first position and positioned outside of the membrane housing when the membrane housing is in the second position; and a syringe connection extending from the first end of the housing, the syringe connection configured to be secured to a syringe barrel, characterized in that: the collet connection is moveable between a first position where the collet connection is configured to receive the membrane housing and a second position where the collet connection is configured to be secured to the membrane housing, and the collet connection comprises a collet body and first and second arms (72, 74) extending from the collet body away from the first end of the body of the vial adapter, the first and second arms (72, 74) defining a space configured to receive the membrane housing.