Did the HB check out. I don't know if their product has the life span I look for in this type of instrument. Talking several decades for the fish-eye Sun. Plus, it still works as it did when new... just not the latest technology.
So, I have a light that "works good." I'm wanting a timing light that works great. Plus, I have a few other Actron products that are known-quality performers.
The little knob aids in checking timing advance settings, I think. I'll know more when the unit arrives this Friday.
Monte