Westland Potting Grit is ideal for mixing with compost to provide extra drainage and open up the compost structure. It’s also great for creating a decorative finish on pots, containers, rockeries, ponds, aquariums and alpine plantings.Washed and graded 4-7mm grit. Improves drainage & opens up structure. Decorative finish for pots, containers & rockeries. Adds weight to pots & containers. Ideal for anchoring aquatic plants.