To my new hammer drill I bought this set to and collected very good experiences with it. In spite of the heat that is generated is not one of the drills has become broken or crooked. All survived the application without prejudice! I'm very satisfied, also because the drill has been delivered very quickly together with the hammer. However, I recommend drilling the simultaneous use of a vacuum cleaner .... the drill make really a lot of dirt), or transport them a lot of dirt out of the hole.