Nikken RAC Boring Heads feature a precision ground serration, giving perfect contact and balance between the holder and head. RAC heads have been designed for large diameter boring operations and roughing. Available as standard on Nikken 2-Lock for both BT and DIN tapers our boring base holders also offer the benefits of dual contact for both flange and taper on suitable machine tools (2-Lock is also fully compatible with standard BT/DIN type spindles). 2-Lock increases the contact area considerably from around 44.4mm to 63mm (BT40) and also, as with all our NC tooling products, provides users with over 80% taper contact as standard. Additional standard options of course also include HSK and Nikken Polygon tapers.