Based on our own experience, these Bi Metal YIDEMIL General Purpose Mandrels are the perfect choice for any industrial and scientific cutting needs... Their durable construction ensures they ARE built to last and provide precise cuts every time. The mandrels also come in a variety of sizes and are compatible with most hole saws. The only downside we found was that they are a bit pricier than other mandrels on the market, but the quality more than makes up for it. Overall, we highly recommend these mandrels for any cutting tool collection..