6.4. | The outer surface of retro-reflecting devices must be easy to clean. Hence it must not be a rough surface; any protuberances it may exhibit must not prevent easy cleaning. | a0c0 |
6.4. | The outer surface of retro-reflecting devices must be easy to clean. Hence it must not be a rough surface; any protuberances it may exhibit must not prevent easy cleaning. | a0c0 |