Premium Material: Made of high quality material, durable and convenient to use. Wide use: suitable for automotive manufacturing, mold making, machinery manufacturing, etc. More Safety: Eliminate the dangerous temptation to withdraw the collet shank, extend the drill bit to reach the full depth of cut. Safety Notice: The extension rod should be snug, 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