The original blades that came on the mower were 5/16" thick. I've been mowing 5.5 acres and after 4 months, I've had to sharpen them twice. When they required a third sharpening one was bent so I tried these. After two mowings the blades are still near factory sharp and cutting heavy pasture grass beautifully! I liked them so much I purchased a second set to have a backup when its time to sharpen these. Highly recommended!