ini kali jawabannya... (kalo minta translate ama Deri aja tu, lg blajar TOEFL)
http://wapedia.mobi/en/Headlamp?t=3.
3. 1. 2. 1. 2. European system
The traditional European method of achieving low and high beam from a single bulb involves two filaments along the axis of the reflector. The high beam filament is on the focal point, while the low beam filament is approximately 1 cm forward of the focal point and 3 mm above the axis. Below the low beam filament is
a cup-shaped shield (called a "Graves Shield") spanning an arc of 165°. When the low beam filament is illuminated, this shield casts a shadow on the corresponding lower area of the reflector, blocking downward light rays that would otherwise strike the reflector and be cast above the horizon. The bulb is rotated (or "clocked") within the headlamp to position the Graves Shield so as to allow light to strike a 15° wedge of the lower half of the reflector. This is used to create the upsweep or upstep characteristic of ECE low beam light distributions. The bulb's rotative position within the reflector depends on the type of beam pattern to be produced and the traffic directionality of the market for which the headlamp is intended.
http://www.ratwell.com/technical/BoschH4.html" onclick="window.open(this.href);return false;
![Image](http://www.ratwell.com/technical/BoschH4/EuroLens.jpg)
While both lamps look similar from the front, there is a characeteristic difference that distinguishes each unit: the Euro unit has a built in shield that covers the front of the bulb.
One of the purposes of the shield is to limit unreflected light from the low beam filament. The reason it is not present on the motorcycle unit is that the shield is not designed for the vibration produced while riding which may cause it to break away.