Specialty seals are specialized or proprietary products and accessories related to seals and sealing. They are manufactured according to customer specifications and designed for specific applications. Specialty seals or custom seals can meet demanding operating conditions. For example, specialty extruded seals for doors and windows offer excellent compression resistance, superior weatherability and chemical resistance, and low friction. Foil seals are safety seals indicate whether a container, package or enclosure has been opened. They provide visual evidence of product tampering. Specialty O-ring seals are similar in shape to a thick rubber band. Specialty O-ring seals are usually round, but are also available in rectangular, oval, or trapezoidal shapes for creating a watertight seal. Specialty gaskets are usually made of rubber and designed to prevent discoloration or odor absorption. Hermetic sealing is used to create a vacuum or leak-tight seal, insulate or channel electricity, or prevent the ingress of unwanted environmental contaminants and particles. Heat seals are flat, flexible, adhesive connectors that are bonded by heat. Industrial sealing is used between surfaces to contain fluids and prevent leaks.