Diameter range: 4.87mm ~ 20.12mm.4~6xD boring depth. Good balance condition is maintained.● Quick Change. Replace end mill or reamer in small hole boring. Shank is Ø20mm. ● Each division 0.01mm, no back lash.● Boring size below Ø6mm, using modified solid carbide end mill as a Boring tool. modification is needed.● Boring size above Ø5mm, using solid carbide shank, insert type. modification is needed.● Apply for electronic parts and micro machining parts.