Reed relays utilize two reed switch blades of a ferrous nickel construction and encapsulate them in an evacuated glass capsule, thus allowing for the remote control, via a coil which generates a magnetic field to close or open the reed switch. With up to 15kV of isolation at 3 amperes of current, these are very compact and efficient devices – even the smaller ‘S’ sized packages can provide 5 to 10kV of isolation. Reed relays are often used in HV test systems, ATE, cable testers and medical defibrillators, amongst others.