Air filtration

This is a split system heat pump with the return air chase at the bottom of the air handler in a hallway closet. The unit was working properly but there is quite a bit of dust accumalation in the return air plenum and one filter installed and one filter missing.

My question is the device in the photo. It is made by Honey Well and has enviracare written across it. Anyone familiar with it? Is a some type of electric percipitator?

Electronic Air Filter. They work great especially if you have allergies. Behind the cover there should be 2 aluminum screen filters and 2 electronic filters. Turn the unit off, remove the cover and inspect the filters. If they are dirty, just put them in the dishwasher and run a full cycle. Drip dry and re-install.

Yuppers, those things are great, especially when coupled with a UV light, the combination eliminates virtually all allergens in the system.
I have no idea how to actually test the unit, I just make a notation about the presence and the physical condition and that is was not tested further than that.