SEELOC® self-sealing washers are ideal for large or odd-shaped through holes, and can be used with any standard screw, bolt or nut. Silicone rubber is the standard sealing material. For applications that are subject to wetting with petroleum products or highly caustic cleaning agents, other materials are available. Washers are UL Recognized for Type 4X and Type 6 enclosure protection and are available for Imperial sized screws from #6 to ½ inch thread sizes. Metric sizes are also available as a special order.