Plastic bottles for laboratory use are made of impact-resistant materials that resist breaking when dropped. Plastic is lighter than glass, making large plastic bottles and jugs easier and safer to handle than glass. Plastic is also better suited for low temperatures but can leech chemicals, depending on the substance and plastic composition. Wide-mouth bottles have easier access to liquids, powders, and solids than narrow-mouth bottles. Narrow-mouth bottles provide accurate pouring of liquids and granules. Rectangular bottles store more efficiently than round bottles and won't roll when on their side. Dispensing and dropper bottles allow workers to obtain small quantities of liquid in a controlled manner. Media, cell culture, and specialty bottles store samples, cell cultures, and buffers. Lab centrifuge bottles have stiff sides to support forces encountered during spinning.