I some time ago bought the #10 and #4F blades to try thinking it wouldn't be much good, I found them exceptional so I have since ordered and received #40, #10 and #4F with spare cutting blades for all, I have 4 Bedlington Terriers and their wool coat dulls blades quickly and because I live rural it is not economically viable to send blades for sharpening, I groom my beddies every 3 to 4 weeks and when not entered in shows where I must scissor I use the 4F on their body coat it cuts like butter and I am so impressed these will be the only blades I will use in the future, it is well over 12 months since my original purchase and haven't as yet had to replace the cutting blade, I am also a breeder and use the blades on the puppies, I absolutely love them