Loop yarn is a kind of fancy yarn, generally by the core line, pressure line (sometimes also called reinforcement line), decorative wire three parts. Core and pressing line often use chemical fiber filament or acrylic fiber a kind of wool spinning raw materials to make yarn to use.

The decorative yarn is the part of winding on the flower twister, which can be yarn of various wool spinning materials or cotton roving. The finished yarn of the circular yarn has regular circular effect, hence the name.