This standard BS EN 4166:2004 Aerospace series. Clips, spring tension, three parts. PTFE bushes is classified in these ICS categories:
49.080 Aerospace fluid systems and components
This standard specifies the characteristics of PTFE bushes for three part clips, spring tension for applications at a maximum temperature of 260 °C, for aerospace applications. They shall be assembled with parts from EN 4167 and EN 4168.