Roller bits are mainly divided into two types:

   i) Metal sealed roller bits

   ii) Rubber sealed roller bits

Metal sealed roller bits main applications:

   a) Adopted high-speed bearing metal sealed technology, long available time under the screw drilling condition.

   b) High efficiency cutting edge and structure to improve drilling speed.

   c) Cutter shell self-protection shape to reduce abrasion of detritus and unbreakable rock.

   d) Best choice for directional well, horizontal drainholeand horizontal branch wells.