This gizmo makes it possible to run LED (or other low-energy bulbs) from a Timeguard timer switch. It is reasonably easy to fit, though it might be a little tricky to fit through the ceiling hole in some cases.
Without the ZV900, it was necessary to put some incandescent bulbs in the fitting to provide enough current to work the timer switch. If all of the bulbs were LEDs then they would glow brightly and flicker constantly when they were supposed to be off. With the ZV900, the LEDs do what you would expect - off when they should be off and on when they should be on.
BUT... occasionally, the lights will flash briefly. This usually happens when another light in the house is switched on or off, but sometimes it happens for no apparent reason.
That is a small problem compared to the savings from now being able to use 100% LED bulbs with the timer, but it is just a little bit irksome.
Solve flicker and glow problems with LED light bulbs
Bought a LED light fitting for a room where I had a security timeswitch in place and the KED bulbs kept faintly glowing even when lights switched off at wall. On fitting the ZV 900 it immediately solved the problem, no more glow from the LED bulbs when switched off at wall despite initial doubts from my electrician who didn't understand how it worked, but accepted that it did.
I encountered an unexpected problem when I replaced incandescent bulbs with LED down-lighters in a circuit controlled by a TimeGuard dusk sensitive switch: When the switch was in the OFF state, the LEDs glowed faintly. The ZV900 effectively cured this problem.