LG1 stands for "Light Guide 1", and was the name for e*thirteen's first direct mount bashguard chainguide, launched in 2006.

In fact when the LG1 launched, it didn't have a bashguard at all, it offered super-light chain retention without impact protection. The bashguard, or taco was added the following year. 

The guide was a lightweight descendant of the original SRS guide, and little known fact, the taco bashguard you could add on was actually machined out of a Supercharger bashguard.