Premium Material: Made of high quality material, durable and practical to use(Please receive the promo code on the product page when purchasing to get a more favorable price.) < p>Wide Use: Suitable for automobile manufacturing, mold making, machinery manufacturing, etc. More Safety: Eliminate the dangerous temptation to remove the collet shank, lengthen the drill bit to obtain the full depth of cut. Safety Notice: The extension rod should be tightened securely, but the collet nut should only be tightened with the same pressure as any router collet . Please note that the extension rod should be well cooled, but the collet nut should only be tightened with the same pressure as any router collet