Best Friends Creations takes unusual natural rocks and repurposes them into lovely works of art. The rocks are drilled and then equipped with oil reservoirs that we make from recycled glass products. Each rock is equipped with repurposed copper wick assemblies and fiberglass wicking so you never have to replace the wicks. Reservoirs are affixed and sealed with oil resistant sealant. We provide instructions and a funnel for easy refilling. Beautiful and unique conversation pieces. Depending on the size of the reservoir, when lit rock will generally burn 2-3 hours before having to refill. AS ALWAYS... never leave a burning rock or candle unattended and keep away from children.