#1 Pads - Coarse Pads designed to remove the large particulate in heavy wine, typically reds.
#2 Pads - Polishing Pads designed to remove medium to small particulate in wine and add the shine & clarity to your wine. Typically used for white wines.
#3 Pads - Sterile Pads are 0.5 micron (super tiny!!) filter pads that remove the very small particulate in your wine. It is advised you filter with #2 pads before filtering with the # 3 pads. Rarely used, this is generally reserved for wines that just won't clear.
Pads are sold in packs of two, one time use only.