This 17" QX Cylinder Cassette has 10 blades for a close, professional cut & is ideal if you have grass tennis courts or croquet lawns to maintain. You can swop between this & the standard blade in seconds without the need for tools. The 17" QX Cylinder Cassette fits neatly into any Atco, Qualcast or Suffolk Punch 17" petrol cylinder lawnmower (17SK, 17S etc.) built since 1996 & featuring the QX system. QX refers to ‘ Quick Exchange’ & existing owners of these machines will be able to tell if their 17" mower has this feature by the fact that the existing cylinder will slot in & out without the need for tools & is in cassette form rather than a st&-alone cylinder.