This pack includes all the filter pads and media you need for your professional ii filterr the set containsr ehfimech x 2 litres removes all coarse and fine dirt particles from the waterr substratpro x 4 litres for quick colonisation of bacteria and faster decomposition of toxinsr coarse filter pad x 1 large pore sponge giving bio mechanical filtration and even water flow throughr fine filtration x 1 before the water re enters your aquarium fine dirt particles are trapped in the fine fil