Bel-Art Precisionware Narrow-Mouth Low-Density Polyethylene Bottles; 500ml (16oz), Polypropylene Cap, 28mm Closure (Pack of 12) (F10621-0007) Narrow-mouth lab bottle for substance control and containment LDPE body for flexibility, elasticity, and impact, stress-cracking, and moisture resistance, and is lightweight Cylindrical shape for a wide variety of applications that require solution containment Screw-on polypropylene cap secures contents to help prevent spills and evaporation