Thanks for your review of the diamond core drills Ron, we're happy to hear they worked well for you. Because the core drills are intended for producing a hole rather than a core we have up to this point not made the inner core specification details available to view. However, after your request we have now added the inner diameter specs to our Bottle Neck Diamond Core Drills and before the end of this month will make sure each of the sizes of the diamond core drills also state their inner diameter sizes. This information will be shown under the technical tab on the product pages. Thanks once again, your comments have been really helpful.
