This European Standard specifies the required characteristics for four types of heat-shrinkable polyolefin sleevings for use in aircraft electrical systems at operating temperatures between − 55 °C and 135 °C. Type A: Very flexible, flame retarded, shrink ratio 2:1 This sleeving has very good flexibility, is flame retarded and will shrink at low temperatures. It is suitable where sensitive components and delicate wiring need protection from excessive heat during shrinking. Type B: Flexible, flame retarded, shrink ratio 2:1, 3:1 and 4:1 This sleeving is flexible and flame retarded. It is suitable for general purposes and is available with high shrink ratios. Type C: Flexible, not flame retarded, shrink ratio 2:1 and 3:1 This sleeving is flexible and not flame retarded and is available in two shrink ratios. Type D: Semi-rigid, flame retarded, shrink ratio 2:1 This sleeving is semi-rigid and flame retarded. It is suitable where strain relief and mechanical support are required