Sintered Diamond Core Bit 1 1/4" Dia. x 15" Long (32mm x 400mm) 5/8-11 UNC Thread This is the thread size found on our Standard Core Bit Arbors. This is the thread size found on our Large Arbors it is also the thread size on Angle Grinders. Sintered Diamond Core Bits are also known as Diamond Hole Saws. These are professional quality, heavy-duty diamond drill bits designed for use on Stone, Granite, Marble, Concrete, Brick and much more. Sintered diamond drill bits have the diamonds embedded into the metal of the Hole Saw teeth or continuous edge rather than merely "bonded" to the outside. As the teeth wear down over continued use new diamonds come to the surface of the teeth. Sintered diamond drill bits are heavy duty bits designed for long life. Generally, sintered bits will have a long life of 20 to 30 or more times the life of a bonded Grit type diamond drill bit if used properly. The heavy-duty design provides long life when drilling in hard materials such as Brick and Concrete. Water is recommended for coolant and lubrication. Another Amazing Product We have been Manufacturing Tools for over 40 Years in UK. USA Based Seller