This cartridge is available as an optional extra and upgrade to the 6 blade cartridge. It has an extra 4 blades than the 6 blade cartridge and offers a much more finer luxurious cut. The 10 blade cutting cylinder mows as low as 6mm for a golf green finish-perfect for ornamental lawns. You wouldn't use this cartridge on longer grass as it wouldn't cope as well as the 6 blade with the blades closer together- it is for ornamental and low cut lawns only below 20mm.