Made from pure lava rock! Make your FireCan(TM) flames dance!a 5 lbs of natural tumbled lava stonea Fits perfect over the FireCan(TM) burnersa Provides variable flames for a more natural look.WARNING: Volcanic rock has the ability to trap moisture and fracture or pop upon rapid heating. When using lava rock apply heat gradually and at low levels to reduce the release of any moisture or internal steam buildup.