The most common styles are either step-type or chevron-type drag bits.

Step-Type Drag Bits
Step-type drag bits come in a variety of wing counts, steps, and sizes to accommodate drilling in a variety of formations, from sand and clay to shale, limestone, gravel, and more.
Three-Wing and Four-Wing – Three-wing bits tend to drill faster, whereas four-wing bits are longer lasting, more durable, and drill a straighter hole.
VDR Step and VDH Step – VDR Step drag bits develop smaller cuttings, whereas VDH Step drag bits are more durable and are used in harder formations. VDH Step drag bits have longer and wider steps and contain larger carbide for cutting. The quantity of steps is largely determined by the size of drag bit.

Chevron-Type Drag Bits
Chevron-type drag bits are recommended for drilling in slightly harder and more consolidated materials than step-type drag bits, such as hard shales, limestones, and unconsolidated gravels. Chevron drag bits also offer premium bits for water well and oilfield drilling, and the cutting structure is more durable than the step-style drag bit but will penetrate more slowly.

For best drilling results, maintain rotary table speeds between 50 and 60 rpm with light to medium weight on bit (WOB). Harder formations require more WOB.

Simply put, 4 wing bits are the most durable but have the lowest ROP. When making a decision on which drag bit to buy, however, don’t purchase a 3 wing or step just to be able to drill faster. Always remember that damaged carbide cutters slow penetration rates.