Selon is a nylon covered sealing washer which is self-retaining and resistant to oils and fuels, unlike the copper-based items it replaces. Working parameters are up to 200lb/in², and working pressure up to 100°C.
Seloc is a shake-proof washer well known for its ability to resist vibration, the effect of tightening the bolt or nut causing the metal serrations to pierce the rubber, bite into the relative metal surface and thus provide the necessary locking action. The covering of rubber reduces the risk of corrosion that would occur with a normal lock washer by enveloping the scores in the protective treatment on the metal face to give protection against moisture and oxidation.