The 2004-2009 Prius did not come with a filter for the hybrid battery cooling air!
Filtering with little air flow restriction - 1/10 inch holes x 7 layer deep = Filters out all hair and all but finest dirt
Easy cleaning - vacuum in place or Washable if necessary. Much less work than cleaning the fans and the battery!
Passenger can not access - Installs behind grill so passengers can not remove.
Easy to install - one bolt Installation, pictures with instructions
Instruction include how to clean fan and battery if necessary again with pictures.
Bonus Instructions on cleaning your piston rings. (longer engine and catalytic converter life.)
Details:
Pre-cut to fit. Filter is .75 inches deep with 1/10 inch holes in a matrix. (Good filtration little air resistance)
Reviews:
"I received the package and installed it. Very nice product, I actually like that the filter is inside instead of outside to prevent tampering by people in the back seat." J. R., ELMHURST, IL
"The installation went fine, thank you. I appreciate your ideas and efforts to help with Prius ownership! ( I bought a battery installation kit from you many years ago too. ) Thanks again and best wishes for a great 2019 and beyond.
October 2019: I have vacuumed the filter while in place a few times with a shop vac. We have a German Shepherd (aka a German Shedder) dog that often rides in the back seat and this filter has stopped a lot of his hair from entering the protected area." E. R., Yelm, WA

Thanks Works great!
Not bad, easy clean
Great item, easy to install and gives great peace of mind with a dog in the car