Figure 3-97.  Housing, flexible, 3-ring. Figure 3-99. A. Pin, ripcord, terminal; B. Pin, ripcord, intermediate. Figure 3-98.  Handle, steel, ripcord. Figure 3-100. A. Ball, terminal; B. Ball and shank. required strength or if the wrong material has been selected  to make a repair.  New high-tech fabrics are continually being explored,  especially in the area of canopy connector lines and canopy  cloth. Great improvements have been made in the reduction of  permeability of canopy fabrics. Permeability is a measure of  the ease with which a fluid (air in this case) can move through  the fabric. Various forms of silicone and polyurethane  coatings are used to create what we call in the vernacular,  “Zero-P.” Generally, coated canopy cloth is referred to as 0  cfm (cubic foot per minute), and uncoated canopy cloth is  referred to as 0-3 cfm. When we speak of porosity, we are  referring to a measure of the tiny open spaces in the weave of  the fabric. As canopy fabric wears, it becomes more porous  and the permeability increases. 3-27 Specification: Strength: Identification: Common Use: Comment: Commercial N/A .18" – .20" ID 3-ring release systems Brass ferrules Specification: Strength: Identification: Common Use: Comment: A. 55A6480 B. MS70107 (61C4304) Subjected to 8 lb bend test N/A Ripcords and life raft releases N/A Specification: Strength: Identification: Common Use: Comment: A. MS70093 B. MS20664 A. 736 lb B. 920 lb N/A Ripcords  N/A Specification: Strength: Identification: Common Use: Comment: A. Commercial; B. 3516AS8410;  C. Commercial; D. MS70106 Pull-tested to 40 lb min. As marked Ripcord assemblies A. Modern trapezoidal or “D”; B. Martin Baker; C. Mini Helwedge; D. Cloverleaf