Nalge 2006 series Excellent chemical resistance Autoclavable Polypropylene screw caps Rigid, translucent walls Leakproof Closure size for 4 mL bottles is 13 mm; 8 mL , 30 mL and 60 mL bottles is 20 mm; 125 mL and 250 mL bottles is 24 mm; 500 mL bottles is 28 mm; and 1,000 mL bottles is 38-400 mm.