The Industrial and Scientific drill bit promised to be top-of-the-line at an affordable price but after using it in practice, I was utterly disappointed. The drill bit did not make a clean cut and only managed to rip a chunk off the glass surface... Thanks to my knowledge gained in practice, I knew it was a bad product from the start. The only pro was its low cost. i would not recommend this product to anyone in need of a high-quality drill bit..