Cool Blocks will save your expensive blades from overheating. Made from a specially formulated graphite impregnated phenolic laminate. Cool Blocks are self-lubricating, enabling them to withstand the heat generated by blades running at high speeds. Youll eliminate the blade damage that occurs when teeth contact the metal blocks. Best of all, Cool Blocks can be set to completely enclose narrow scrolling blades, protecting their teeth and set. 4 blocks per pack to fit upper and lower guides.