Through trial and error, I found that these drill bits were simply not worth the risk... The bits would randomly stop spinning mid-use causing unnecessary delays and frustration. Not to mention, they seemed to wear down and become dull much quicker than other brands I have used in the past. The only positive aspect was the affordable price. Overall, i would not recommend these to any serious industrial and scientific workers..
Pros
Efficient and easy to use for drilling through different materials.
Cons
Heavier than other electric drills, requiring more effort and strain on the user's arms.