The blades you require are made by ALM Manufacturing
01423 797208
The part number is ALM QT028
http://www.almmanufacturing.com/en/grasstrimmer/grass-trimmer-parts/florabest/item/253-alm-qt028-plastic-blades.html
They are available from your local hardware store, Homebase, B&Q, etc
Richard
April 2013