The Schréder GSO was designed in the 1960s during the period of "airplane" lighting with the GN, ​​​GR​​, GP… Its production stopped in the 1970s to make way for the 2nd generation which continued until the early 1980s.

The GSO consists of: a large transparent or gray painted acrylic plastic protector (it then takes the name GSM) equipped with a synthetic rubber seal, an injected aluminum end cap, two aluminum mirrors and two small wheels at the end of the luminaire to facilitate opening of the protector. It's possible to have the electrical auxiliary incorporated into the luminaire, so it takes the name GSOB.

The 2nd generation has the same components, the two major differences are the casters which give way to aluminum rails fixed by rivets or screws on the protector, which also undergoes a small modification at the end which becomes more round.

The GSO is available in 4 different sizes:

• The GSO 90 for SOX 90W lamp: 977 mm
• The GSO 135 for SOX 135W lamp: 1231 mm
• La GSO 180 pour lampe SOX 180W : 1486mm
• La GSOB 90 pour lampe SOX 90W avec auxiliaires électriques : 1231mm
• La GSOB 135 pour lampe SOX 135W avec auxiliaires électriques: 1486mm
• La GSOB 180 pour lampe SOX 180W avec auxiliaires électriques:  1740 mm
• La GSSO 90 pour lampes SOX 2X90W : 1486mm
• La GSSO 90+55 pour lampes SOX 55W et 90W : 1486mm

In the 1960s, Belgium decided to use 180W low pressure sodium lighting for its major roads and highways instead of fluorescent tubes, the GSO therefore very quickly became a great classic of Belgian lighting and this until in the 1980s. It also lit many central berms before the appearance of the RX but it remained master of the side berms before the arrival of the RX mais elle est restée maître des bermes latérales sur les autoroutes ainsi que sur les grands axes et nationales avant la venue de la ​GZB​-GZM vers 1985. La technologie LED l'a fait totalement disparaître lors du plan lumière 4.0 

Rare examples can be found in the north of France, Luxembourg and the Netherlands.