Compost Pail Container Replacement Filters - Charcoal 4 sets - Fits 1 Gallon Compost Pail INCLUDES  (4) Sets Charcoal Filters / 4 Square and 4 Round Compost Bin Charcoal Filters fits standard 1 gallon capacity pails that require dual charcoal filtration system Filter Dimensions - Round filter is 5 1/2 diameter. Square filter is 4 inches x 4 inches Replace filters every 2-3 months to control orders as needed Eco-friendly charcoal filters