Well perhaps I'm being dim - I assumed a rotating blade machine and guessed after looking on Amazon.
Here- http://tinyurl.com/j3tlwwl
If it has spacers they will be hidden above the blade - when you turn the machine over - below the blade.
4 x ALM FL182 Blade height Spacers For Flymo and Qualcast Machines
Continuing Good Luck..., April 2016