This is a Prebuilt LT2 robot. It is the same chassis that we offer with our tactical LT2 robot. The LT2 treaded robot is lighter weight than the HD2 Treaded Robot. It is a pre-built version of TP-210-002.
This is a very small light sensor. A photo resistor (also known as a photodector, or photocell) changes resistance depending on the amount of light it is exposed to.