Fi-Shock™ Woodscrew Insulators. Looking for a way to safely fasten electrified wire to your wooden posts so they don't become loose and lose energy? Our unique Fi-Shock™ Woodscrew Ring Insulator fits the bill exactly! These insulators have an angled slot that ensures wire retention while allowing easy install. They work with high tensile wire, Powerwire and Power-rope. These electric fence insulators come in black colour only and are bulk packed with 130 in a convenient easy to carry bucket.