Paint Roller Grids 4" Specification: Roller grids are available in several sizes to fit most plastic buckets.These sizes correspond to the size of your roller frame 4-inch grids (12 x 22cm )are perfect for small 1 gallon cut-in buckets and small trim rollers 7-inch grids (18 x 26cm)work best in a 2-gallon plastic paint bucket 9-inch grids (23 x 32cm)are designed for 5-gallon bucket http://www.cohwabrush.com/paint-grid/paint-grids-4.html