This Irwin Blue Groove 4X drill bit set features a patented design for the groove point and cutting edge, enabling 4 times faster cutting of timber than standard spade bits without scraping. The parabolic scoop optimizes control and wood chip removal, while the increased relief angle (12-17 degrees) and larger, durable shank (152mm long) enhance performance. The grooved hex shank prevents slippage. This set includes 8 pieces in sizes 12, 16, 18, 20, 22, 25, 28, and 32mm, all stored in a stackable, connectable ToughCase with a transparent lid for easy bit selection. The case is fully interchangeable with the Dewalt Tough Case Tstak system.