Ultra Core candle wick offers the rigidity of zinc . . . without the metal wire. This product line gives candle makers their independence from using zinc core wicks. Ultra Core is an all fiber wick. It has the rigidity of zinc core without any wire or paper in the core. The core is a specially treated fiber that completely consumes. Since the core of this advanced wick consists of fibers and not metal, it does not leave behind the unsightly metal wire protruding from the flame as it burns. The wick stays straight during the candle fill and more importantly during the burn. This wick is an excellent choice for container candles. Here is a link to a video that explains how to select the size wick you need. https://youtu.be/vYKiF54W0wY Made in the USA