Cap Center Hole: 8mm Cap Screw Thread: 18mm Cap Material: Metal, Magnetic Bottom Type: Round, Flat bottom Part No Description CRX2010-1001 10ml Clear vial, 18mm screw top, Flat bottom, 100/pk CRX2010-1002 10ml Amber vial, 18mm screw top, Round bottom, 100/pk CRX2020-1001 20ml Clear vial, 18mm screw top, Flat Bottom, 100/pk