This is not a professional quality product but is intended for homeowners who sometimes need a longer drill bit and can be very careful when using it. They do a great job for the price. Don't push them too hard or they'll bend - let the drill do all the work, and if the dust doesn't come out of the hole, pull them out properly and unload the sawdust when they start to slow down. In any case, this is a good product for the price, but be careful with it.