Surge Protection & Safety Capacitors Syfer / Knowles Surge Protection and Safety Capacitors comply with international UL and TÜV specifications to offer designers the option of using a surface-mount ceramic multilayer capacitor to replace leaded film types. With simple pick-and-place assembly, reduced board space, and a lower profile, these capacitors are approved for voltages up to 250VAC. Syfer / Knowles Surge Protection and Safety Capacitors are available in a FlexiCap™ version to reduce the risk of mechanical cracking.