DonFiber ST Type I High performance steel fibers with hooked ends for reinforcement of concrete and mortar (Formerly known as ST Fiber Type 1) You might also be interested in DonFiber PP Macro E High-performance corrugated macro polypropylene fibres DonFiber PP-F High-performance fibrillated polypropylene fibers DonFiber ST300 High performance corrugated steel fibers for reinforcement of concrete and mortar DonFiber PP1000 Fire spalling resistance micro polypropylene fibers