Many times it is desirable to electrically isolate one piece of a sample holder (say) from another. Now it is really easy to do and it is reliable, too. Available in standard screw sizes, these handy little gizmos have dozens of uses around the lab. Made from 98%+ Al2O3 (alumina), these non-porous washers are robust, fully vacuum compatible and bakeable to over 400°C. Precision size control avoids errors due to accumulation of tolerance in large or multiple stack-ups