Diamond Core Drill Adapter. M16 female to 1-1/4 male. Water feed Adaptor Diamond Core Drilling 16mm FEMALE TO 1-1/4unc. This adaptor will allow you to use the diamond wet core bits. Made from high quality steel, tempered and hardened. Please be sure to switch to your tool to drilling mode (without impact). Photo: photo of original listed item you will get what you are see in photo.