This patent covers EGS's upside down pulley cage - as used on the EGS Up Cage derailleur.
The images appear to suggest the use of a fully enclosed chainguard. This would be a welcome development for commuters - but is not exactly the look favoured by the immeasuably cool, radical, French downhillers who actually ended up using the EGS Up Cage!
Browse associated derailleurs.
EGS Up Cage 1998?