Used as an alternative to hotplates and Bunsen burners, heaters and heating mantles allow for direct contact with glassware without the fear of shattering because the heating element is typically insulated from the container. As a result, heaters and heating mantles can provide round bottom flasks with uniform heat distribution. Fabric heating mantles are foldable, allowing them to be used with numerous flask shapes and sizes, while rigid heating mantles are generally less prone to tearing or spill damage. The temperature for heaters and heating mantles is usually controlled by a rheostat, which makes maintaining temperature simpler.