Bottle adapter size is listed according to nominal interior bottle diameter in mm. Measure inside diameter of bottle opening with a ruler to determine size needed. Actual fits are:
ENBA12, 12 - 14.5mm
ENBA14, 14 - 16.5mm
ENBA17, 17 - 20.5mm
ENBA19, 19 - 22.5mm*
ENBA24, 23.5 - 25.5mm
ENBA27, 25 - 27.5mm*
ENBA31, 30 - 33.5mm
* Note that no adapter will fit a bottle opening from 22.5 - 23.5mm and 27.5 - 30mm.

Description:
Variety of sizes intended to meet most common medication bottles.
Use with ENFit syringe to extract medicine from bottle. DOES NOT fit Luer, Oral or Bolus syringes.
Fits inside bottle opening to allow continued use of childproof caps.
Ideal for aseptic technique.
Made without natural rubber latex, DEHP, Bisphenol A (BPA) or other phthalates plasticizers.
5, 20, or 100 pieces per pack.
Picture shows all 7 sizes. Only 1 size comes in a pack.