Okay, I ordered them.  I'll try to remember and report my thoughts after I get them and try them.

Thank you for the suggestions and taking the time to reply.

Reading I noticed that the 6 implies that these are commercial grade, there's a 3 which is lower quality and softer and a 5 which is higher quality and harder.  These 2 (3 & 5) are geared for consumers with the big box type mowers.  ( I think)