What is a calibrated puzzle interlock without a bevelled edge?

A calibrated puzzle interlock without a bevelled edge is produced by cutting each rubber tile precisely to size from a larger blank. The blank is left to cure for several days before cutting.

Without a bevelled edge means that the tile edges are vertical rather than chamfered. The finished tile has only a minimal height tolerance.

In the usual pressing process, a rubber tile receives a bevelled edge, causing each joint to appear as a dark line across the surface. With vertical edges and minimal height tolerance, the tiles butt together accurately, leaving only a hairline joint. This hairline joint is visible in the laid surface only on close inspection, so the floor covering appears almost seamless.