How to choose a good quality core drill

How to choose a good quality core drill ? Used magnetic drill drilling engineers may have distinct magnetic drill drilling speed really is not an ordinary hand drill comparison . Good times but the price is hollow drill twist drill head . So buy the right track to good hollow drill manufacturers consumption is very important. So what kind of Concrete saw blades  hollow drill core drill is considered good ? How to choose a good quality core drill ?
I have talked to many customers about this topic. The answer generally have few , there is a trust -based client that is collaborative and after some suppliers will have great confidence in the products are supplied to provide a good product . We will also improve our quality selection system for customers good quality first hurdle ; Some customers are advocating brand type , or some kind of a common brand name products compared to agree , so the time of purchase , know or direct purchase of a certain category diamond blade saws  of branded products, other brands of products to try ordinary little or rarely use . Such customers rarely have the opportunity general more suitable to my contacts , products are often cut in , it may be said that many customers will be repeated after it was selected choice of a particular brand of product , and continue to have a good use after the course Some big brand products are indeed the passing rate on the quality control and quality management is 4 inch saw blades  very strict, so there is little "winning " situation attack. Another type of customer choice hollow drill bits, to simply learn to pragmatic type , I thought it only appropriate choice , either the price or quality , some brands may know very well , but the quality is not his only reason for choice .