These bottles are flexible and feature a narrow-mouth opening that is easy to pour from and is preferred for use with liquid samples. The sloping shoulders facilitate emptying. In addition to the screw cap, a plastic plug insert comes with each bottle, providing additional leak-resistance. Simply insert the plug into the mouth of the bottle prior to closing the lid. This ensures a leak-resistant seal and makes these bottles ideal for transport and long-term storage. The cap and bottle neck have molded-in tagging points which are designed for securing the cap to the bottle using wire security ties. This makes the bottle tamper-evident. This bottle is approved for use with food products.