• it can drill the bigger hole than the casing;
• it can ream while drilling for various kinds of well types;
• it can get maximum space between the casing and hole, improved well quality;
• it can make the casing work more stable in the high dog-leg angle well;
• it can drill the bigger diameter hole in the multiple branches wells;
• it can lower the risk of stick in the big inclination well, swelling ground, flowing ground and exhausted sandstone; 
• it can increase the hole diameter of the production well section, helps increase the output.

The basic theory of RWD products is similar to bicentre bit, the most important geometry feature are: Pass-through size, Pilot size, Reaming size and Reaming angle. The size of pilot bit and reaming blade should be less than the casing size. So the RWD can easily get to the bottom hole. The revolution diameter of reaming blade should be bigger than the casing diameter, so it can ream and drill under the casing.

RWD's innovative design consists of three kinds of products:
　　RWD   : Ream While Drilling
　　SRWD  : Steerable Ream While Drilling
　　STRWD  : Slim hole technology Ream While Drilling