A liquid drug transfer device (100; 110; 120; 130) suitable for use with a drug vial of a small drug vial and a large drug vial, the drug vial including a drug vial bottle, a drug vial interior, a drug vial stopper, an uppermost drug vial surface, and a drug vial closure, the small drug vial having a drug vial closure with an external diameter D1 and the large drug vial having a drug vial closure with an external diameter D2 where D2 > D1 and the difference D2 - D1 is in the range of between 4mm and 7mm, the liquid drug transfer device (100; 110; 120; 130) comprising a universal drug vial adapter (200A; 200B; 200C; 200D) having a longitudinal drug vial adapter axis and a skirt for telescopically clamping on the drug vial closure, said skirt including a top wall transverse to said longitudinal drug vial adapter axis, a first pair of axial directed, spaced apart flex member supports (209, 211) and a second pair of axial directed, spaced apart flex member supports (212, 213) opposite said first pair of axial directed flex member supports for defining a drug vial cavity for snugly telescopically receiving at least a top part of a large drug vial therein, each flex member support (209, 211, 212, 213) having a proximate end (209A, 211A, 212A, 213A) adjacent said top wall and a distal end (209B, 211 B, 212B, 213B) remote from said top wall, said first pair of flex member supports (209, 211) including a first crosspiece extending between their corresponding distal ends (209B, 211 B), said first crosspiece integrally formed with a first flex member resiliently flexibly mounted thereon with respect to said longitudinal drug vial adapter axis, said first flex member having a first flex member free end remote from said first crosspiece and being axially directed and extending generally parallel to said longitudinal drug vial adapter axis between said first crosspiece and said first flex member free end, said first flex member further having an inward radial directed first drug vial grip (221 B), said second pair of flex member supports (212, 213) including a second crosspiece extending between their corresponding distal ends (212B, 213B), said second crosspiece integrally formed with a second flex member resiliently flexibly mounted thereon with respect to said longitudinal drug vial adapter axis, said second flex member having a second flex member free end remote from said second crosspiece and being axially directed and extending generally parallel to said longitudinal drug vial adapter axis between said second crosspiece and said second flex member free end, said second flex member further having an inward radial directed second drug vial grip, said first flex member and said second flex member being opposite such that said first drug vial grip (221 B) and said second drug vial grip define a separation S therebetween where S < D1 whereupon said first drug vial grip and said second drug vial grip underlie a drug vial closure on telescopically clamping said universal drug vial adapter (200A; 200B; 200C; 200D) on the drug vial, said first flex member and said second flex member being outwardly resiliently flexed correspondingly at said first crosspiece and said second crosspiece with respect to said longitudinal drug vial adapter axis,to a greater extent on telescopically clamping said universal drug vial adapter (200A; 200B; 200C; 200D) on the large drug vial compared to telescopically clamping said universal drug vial adapter on the small drug vial whereby to accommodate the drug vial closure of a small drug vial or a large drug vial, when the difference D2 - D1 is in the range of between 4mm and 7mm.