rings under the risers facing back instead of forward of the risers facing front or varied the geometry of the rings for example using an elongated middle ring for a claimed improvement in mechanical advantage on Aerodyne's miniforce system. Safety concerns Since the introduction of the 3-ring system, variations in the design have raised safety concerns. For example, the move to mini rings and mini risers caused riser failures on some designs until riser strength was improved. The failure of some manufacturers to include stiff riser inserts and other hard housing cable guides to allow the free movement of the cutaway cable when risers and webbing are twisted has caused difficulty in cutting away from malfunctions with riser twists or harness deformations. The tolerance in the manufacture of the fabric risers and their connection to the rings is critical in maintaining the mechanical advantage of the 3-ring system and this has been compromised in some designs. Reversed risers placing the rings under the risers has prevented the rings moving freely and releasing under some cutaway scenarios. Replacement of the Lolon-F coating with Teflon impregnated compounds has caused both cracking and cable stripping problems. Maintenance Regular maintenance of the 3-ring system and risers is essential. Manufacturers recommend that the risers be disconnected from the harness and flexed, the rings should be checked for cracks or corrosion and the cable should be removed from the housing, cleaned and lubricated, typically with silicone based lubricant. References Parachuting