GC-13,GC-19,GC-25 Curved, for 13mm,19mm and 25mm grooves out of polystyrene boards & blocks Designed to be used with KD-5G GC-13,GC-19,GC-25Curved, for 13mm,19mm and 25mm grooves out of polystyrene boards & blocksDesigned to be used with KD-5G Hot Knife Cutter Blade