V-COIL - 4.2mm - Rapid STI-Drill Bit. These drill bits has been manufactured by VÖLKEL and are part of the V-Coil brand, with 100 years of experience in manufacturing screw taps, VÖLKEL has become one of the worldwide leading suppliers for threading tools. Application: Core hole enlargement of the existing damaged or worn out thread application flexibility with 1\/4 Hexagon Drive to be used by hand or cordless powertool handy, even in awkward places more compact than the standard This is not a stock item therefore please allow 1-3 working days for dispatch. As this is not kept as a stock item, this is non-returnable & non-refundable. V-COIL - 4.2mm - Rapid STI-Drill Bit