Review on Efficient Installation: KATA 19 152mm Mandrels for Plywood Projects by Robert Prix

Don't let the cost fool you. They're cheap for a reason. These bits cannot drill 1/2" T1-11. I've used them several times in different applications, different size holes and got the same results every time. They burn through wood better than they cut it. When used for drywall, then they are good but for most common woodwork they are useless, buy a better quality set or exactly what you need.