Silicone rubber is a unique synthetic elastomer that is made from a cross-linked polymer which is reinforced with silica. It's advantages include durability and flexibility, non-stick anti-adhesive properties, low chemical reactivity, its ability to repel water and form water tight seals, low toxicity, good thermal stability, excellent resistance to oxygen, ozone and sunlight and good electrical insulation. There are four main molding methods for manufacturing silicone rubber prototype and production parts: liquid injection molding, compression molding, transfer molding and extrusion molding (also refered to as "extruding" and "extrusion")