The CYL-9 multiconstruction drill bit series is perfect!! Especially when the drills are new, they can drill through steel with a hand drill (I have tested up to half an inch thickness) without wandering, without slipping, and with unprecedented ease.

I was excited because I had seen very good reviews in various tests, but as soon as I tried it to drill a wall, I was disappointed.... because it was crooked. I ended up using a cheap one and it opened a perfect hole. The chuck on the drill I have is one of the few that is concentric.

Perfect drills for all surfaces, very durable and effective. They are worth their money and more! I use them for tough surfaces like hard concrete and they never stop