These are aluminium oxide benchstones that have been ground flat and square to a high degree of precision.
The main application for these stones is to check precision surfaces for burrs and damaged areas with raised material and to remove those blemishes.
The very flat stone will only cut if it hits a small surface area (like a burr), once that burr is removed, the stone will hit the entire surface and is not able to cut any further.
The stones come in a pair, and before each use they are rubbed against each other to remove any metal or abrasive particle that is sticking out the ground surface.
Then they can be applied to any clean precision surface and used like a regular stone to remove burrs and raised material.
They will – if used properly – Not scratch a surface, remove material or create a grind lay.
In fact, they can improve the finish of a surface almost to gage quality, as demonstrated on this worn gageblock:
There are two versions, standard, just a rectangular block with the four long sides ground (the two smallest faces are unground) and a version with a lip on one of the long, narrow sides. This lip is there to get the stone into and under a grind relief as shown in the pictures:
How to order
Email with name, adress (and company name / VAT Number): email@example.com
Price for a pair of stones: 90,20Eur (including 19% VAT) + Shipping via DHL
(Depending on the country of delivery, Most of Europe will be 15Eur shipping).
Payment after delivery (Within 14 days via bank transfer or PayPal)
No sale outside the European Union.