karcher 91840180 OEM Valve screw

I ordereds new blades for my cub cadet riding lawn mower. The new blades arrived in 5 days. When I opened the box and inspected the new bladews they were different then the originals, in that the center hole was not star shaped. I sent an Email to OEM and with in hours ( 3 or 4 ) I recieved a phone call from Mark min ustomer service. He assured me this was a new design and stronger than the old 6 point star pattern. I was not convinced so early the next morning I put the new blades on. They fit perfectly and are great. The first cut was even and the sound of the tractor there was no strain . They cut perfectly and effertlessly.
Thank you OEM for you customer service,quick delivery and a great product . I highly recommend this company.