Style CG windings and construction is similar to the Style R however it has a solid Outer (centering) ring securely fitted. This is the most popular style of Spiral Wound Gasket
Style CGIR windings and construction is similar to the Style CR however it has a solid 3.2mm thick Inner ring fitted into the gasket bore. Commonly used in arduous or critical service conditions.
Style R is the basic sealing element which is constructed with a V-Shaped (or Chevron) metal strip and a soft inlay filler strip. Commonly used where space is a premium and only light bolt loads are a available.