Matco MU4A 3/16" to 7/8" Unibit Step Drill USA | eBay
LARGE HYPER-STEP HIGH-SPEED DRILL BIT SET, 4 PIECE DB4HSL | Matco Tools
Matco Tools - Have you met the 2 new members of the Hyper-Step family? The already awesome, Matco EXCLUSIVE Hyper-Step drill bits are proud to be joined by the NEW DB4HSL Large