Irrespective of its dimensions or power class, an ERCO lighting tool is characterised by properties such as high visual comfort, advanced lighting technology, durable materials and appropriate design. This approach gave rise to Jilly, which was initially designed as a range of spotlights for halogen lamps up to 100W, but was then expanded by the addition of a line of floodlights for halogen, metal halide and compact fluorescent lamps. This allows Jilly to cover a further area of washlighting and highlighting tasks. Knud Holscher, Quinta's designer, found a neutral, elegant, smooth-finished form for the Jilly range which blends in with every style of architecture.

The housing and bracket are cast aluminium and the electrical wiring is contained internally. All Jilly spotlights have a slightly protruding, matt black anti-dazzle ring and a cross-baffle covering the light aperture. This is the visible expression of the careful measures taken to restrict glare, resulting in optimum visual comfort. Jilly floodlights also feature a high cut-off angle thanks to their special reflector geometry. Their compact dimensions make Jilly spotlights and floodlights ideal for use in areas such as home lighting, shop windows and shops as well as exhibitions or galleries. For mounting on 3-circuit track, the Jilly spotlights for low-voltage halogen lamps, like the floodlights for high-pressure discharge lamps and compact fluorescent lamps, are fitted with a transadapter; the other versions have a 3-circuit adapter. The DALI-compatible luminaires feature digitally addressable control gear, which can individually address every single luminaire, i.e. using the ERCO Light System DALI and the pre-programmed ERCO Light Studio software.