Item Type: Auxiliary Tool Holder Product Material: 20CrMnTi Product Model: TB20 20-ER20A Square Size: Approx. 20 x 20mm / 0.8 x 0.8in Product Length: Approx. 132mm / 5.2in Application: Suitable for ER 20 Package List 1 x Auxiliary Tool Holder 1 x Storage Box Ask professionals to operate. 1Fine Workmanship: Forged in vacuum quenching furnace to achieve carbon and oxygen co infiltration, increase hardness and enhance service life. 2Centre Hole Design: The central through hole design can facilitate water cooling, effectively suppress vibration and increase shock resistance. 3Universal Using: A square tool holder that can be used to hold tools of various diameters, which has good versatility and reduces processing costs. 4Great Material: Made of premium 20CrMnTi, not easy to deform, also has excellent durability for long term use. 5Easy to Carry: The box will largely simplify the storage and carrying as well, and the installation is very easy.