Aluminium Profile (also called Channelling) for LED strip lighting, is used to protect the strip light, and defuse the light through the plastic covers provided. It is also acting as a heatsink to keep strip light within safe operating temperature (to preserve light quality). Normally sold per meter, and transported in 2 meter lengths typically. End caps and mounting clips available for most types. Many more profile types available then are list here, so can source specific types should something specific be required. Specific lengths can be cut including corners. Different plastic covers also available for certain types eg, Opal, frosted, or clear.