Listings commonly highlight 1/4" pebbles and finer grades (1/8"–1/4") for succulents and mini pots. 1/2" sizes are more often noted for bonsai or larger top-dressing uses.
The listings show sizes from about 1/8" up to 1/2". Several items are 1/4", and some white pebbles are noted as about 0.5–0.7".
Listings describe natural river gravel/pebbles and volcanic/lava rock; some items are labeled as manufactured stone or simply listed as stone.
They are commonly used for top dressing and soil amendment for succulents, cacti, bonsai and terrariums, and as vase or bowl fillers. Other uses shown include landscaping, aquariums, fairy gardens and similar decorative projects.
Listings describe these materials as porous: they absorb and slowly release excess water, improve soil aeration and reduce compaction, help prevent root rot and overwatering damage, and can be used as a drainage layer at the bottom of pots.