Van Ness Zeolite Air Filter for Litter Box are coated filter pads which removes ammonia odors from the air. For best results in maintaining filter effectiveness, always remove solid waste from pan as soon as practical.
The zeolite filter removes urine odor before it leaves the litter box. You need to change the filter every 90 days.
You use 1 filter for CP6, CP6TR and CP66.
You use 2 filters for CP7, CP7TR and CP77.
The measurements are 6 1/2" x 4 7/16" x 3/16".