The K6 was based on the Nexgen 686. AMD bought Nexgen and used there RISC86 core which allowed much higher speeds then the old K5 core.
K6's were made on 0.35 micron process originally and then moved to 0.25 micron in 1998. For a while AMD used a PR rating to equate the K6 to the Pentium II, but since the PR was the same as the actual speed, it was dropped.
This is a 0.35 micron part.
This is a somewhat rare version with the large 'K6' logo on it.